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				<title>C4owners : FAQ.</title>
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				<description>The Citroen C4 - everything you need to know about owning a C4</description>

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				<copyright><div class='justify2'>All trademarks are Copyright © their respective owners, All product names mentioned herein are the trademarks of their respective owners. In addition, images, logos, pictures or other material may be trademarks, registered trademarks or © Copyright of their respective owners and should be respected as such. All other Content is Copyright © c4owners 2006-2010 |  <a href='http://www.c4owners.org/Privacy.php' title='C4owners Privacy Policy'>Privacy Policy</a>  |  <a href='http://www.c4owners.org/contacts.php' title='Contact Details'>Contact Details</a>  |  <a href='http://www.c4owners.org/gsitemap.php?show' title='Sitemap'> Sitemap</a> | <a href='{e_PLUGIN}rss_menu/rss.php'>RSS Feeds</a>This site is independently owned and run and is not an official Citroën site. It is run by and on behalf of C4 owners for the benefit of others who own or are thinking of owning a Citroën C4 now or in the future.Technical information or personal opinions given by C4owners members are provided in good faith and for guidance only. C4owners is labeled:     <a href='http://www.icra.org/sitelabel' title='Labeled By ICRA'><img src='{e_IMAGE}icra.gif' alt='Labeled by ICRA' style='vertical-align: middle; border: 0;' /></a> No responsibility can or will be accepted for loss or damage arising out of such information. If in any doubt, please refer to your local Citroën specialist or dealer before undertaking any work.Any information or views expressed in posts in the forums on this website are those of the poster and not those of C4owners.org - Website created by <a href='http://www.nwm-online.co.uk' title='Site Creators'>NWM ONLINE</a></div><div class='center'><a href='http://www.spambotsecurity.com/zbblock.php' title='ZB Block, GPL PHP Website Spam and Hacking Prevention System' style='letter-spacing: -1px; font-size:8pt; background-color:#FFFFFF; text-decoration:none;'><font face='Verdana, Arial, Helvetica, sans-serif' color='#000000'><strong> Protected by : <font color='#FF0000'>ZB BLOCK </font></strong></font></a></div></copyright>
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				<pubDate>Fri, 10 Sep 2010 12:51:36 -0500</pubDate>
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					<description>The Citroen C4 - everything you need to know about owning a C4</description>
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						<item>
						<title>C4 Depollution System Faulty / Engine Management Light on</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.5.216</link>
<description><![CDATA[C4 2.0 HDi has the following error codes: P2408 Fuel Cap Sensor / Switch Circuit, P0470 Exhaust Pressure Sensor A Circuit &amp; P1429 Electric Air Pump Primary failure.Having driven and reset the code a couple of times the error: P2408 Fuel Cap Sensor / Switch Circuit keeps coming back and if I leave it long enough the P0470 Exhaust Pressure Sensor A Circuit also returns.I have been told by a dealer there was an issue with the original Exhaust Pressure Sensor. You now replace it with a different sensor, additional pipe and bracket for the pipe.Solution:Replaced the Exhaust Pressure Sensor and yes it did need a new bracket. This was in fact located under the Battery mount (Which needs to be removed) in the enguine bay. I did not replace the hoses however as to remove the clips from the exaust end would seem to need the removal of the exaust. All it took was a litttle turning/twisting of the hoses in place and they attached quite comfortably to the new sensor.]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.5'>Known issues</category>
<author>noauthor@nospam.com (Macsimp)</author>
<pubDate>Wed, 08 Sep 2010 22:45:38 -0500</pubDate>
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						<title>Can I fit a spare wheel and carrier to a C4 Grand Picasso - C4GP</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.2.215</link>
<description><![CDATA[I have just bought a 2007 C4 Grand Picasso and have a pristine puncture kit and air pump. What I would like is to have a spare tyre. The C4 handbook suggests there could be scope for under car storage. Is there a kit I can buy to do this in the Grand Picasso?Maybe spares for the C4?I know it isn't possible on an Exclusive due to the Pneumatic suspension.Answer:Yes it's possible (but not on an exclusive) and you will require the following:C6555T2 - 31R003 Hog Ring x1 @£0.74, C6913V8 - 31R002 Crimp Bolt x 2 @ £0.77ea, C6922C7 - 31R001 Self Taper x2 @ £0.36ea, C6935A6 - 31R003 Nut with Bas x 4 @ £0.14ea C7603Q5 - Z/stack Wheel Open Mechanism x 1 @ £81.10. All in £85 plus VAT. Then you require a steel wheel and tyre - basic is £64 plus vat.]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.2'>How Can I?</category>
<pubDate>Sun, 05 Sep 2010 08:21:34 -0500</pubDate>
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						<title>Retro Fit Front Parking Sensors to a C4GP or other C4</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.2.214</link>
<description><![CDATA[Afternoon all, sorry if this topic has been covered to death but I have done quite a bit of searching on the forum and can't seem to find a definitive answer.Are you able to fit front sensors to the GP that use the display that the rears use so in effect are like the factory fit ones?Some threads seem to say yes, some say no and some say sort of!I have a feeling that if the answer is yes, then it will be [%*^#@!] expensive!!  BigJohnD wrote ...Here's more info on the 9690 01 Front Parking Assistance.It would appear this can be fitted to any qualifying model, irrespective of whether rear sensors are already fitted.9690 01 Front Parking AssistanceSuitable for (amongst others):C4 Berline and Coupé: after 03/09 / O11558C4 Picasso: after  03/09Grand C4 Picasso: after 03/09This product is authorised and is approved, despite the label forbidding the installation of a consumer above 10mA to the reversing lights harness.DescriptionInnovative electronic equipment offering comfort and safety.Very practical on this type of vehicle, during parking manoeuvres this system detects obstacles in front of your vehicle.Parking assistance assists the driver in performing his manoeuvres.This parking assistance guarantees full detection of static or moving obstacles that are liable to be hit by the vehicle.A bleeper signal variable in intermittence indicates the distance between the vehicle and the obstacle.Comprises:1 control unit;4 sensors;1 supply harness;1 switch;1 bag of fixings. Technical characteristics:4 sensors which can be painted, to be fitted into the FRONT bumpers.Passive system with 4 sensors and a sealed connection.A bleeper signal variable in intermittence indicates the distance between the vehicle and the obstacle.Sensitivity to be adjusted (see fitting instructions).Pushbutton control with indicator light.As the distance reduces, the signal frequency intensifies, until a continuous sound invites you to stop your manoeuvre.Audible alert: Buzzer up to a maximum of 74dB.Maximum range: 1m - 1.2m (adjustable via the trimmer: SENS).Power consumption: < 55 mA.Operating temperature: -20°C to +80°C. Sales statementsPrevents the bumpers from becoming scratched and dented.The system is compatible with all types of towbar.The ultrasonic sensors harmonise perfectly and inconspicuously with the bumpers.The sensors can be painted to blend in with the bumpers.The sealed connection preserves the system in perfect condition throughout its service life.The sensitivity of the sensors and the volume of the audible alert can be adjusted, so the owner is free to adapt the system to his own requirements. Fitting instructions:  For C4 Berline, Coupé and C4 Picasso:  ac969001_t1.pdfFor Grand C4 Picasso:  ac969001_t2.pdfThe fitting instructions indicate the "Citroën Service Computer" is required, i.e. presence and activation by Lexia or Proxia.Fitting times:C4 Berline and Coupé: 2.30hrC4 Picasso: 2.30hrGrand C4 Picasso: 2.30hr]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.2'>How Can I?</category>
<author>noauthor@nospam.com (BigJohnD)</author>
<pubDate>Mon, 23 Aug 2010 04:01:36 -0500</pubDate>
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						<title>Petrol, just what is in it?</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.10.212</link>
<description><![CDATA[This is something different but well worth reading. It was written by our learned friend in Stoke and we think is of interest to any car or bike owner.Well…………! In The Beginning there was Carbon and Hydrogen. These got together in accordance with rules forged in the Big Bang (yes, really!) to make methane, one carbon atom with 4 hydrogens stuck on. A bit later, (only 4000 million years) other atoms started getting together and finally came up with Life, a self-reproducing chemical mix. The reproducing bit was quite fun, but after 600 million years even that gets boring.So, a more or less intelligent life-form invented The Car and the Motorcycle, the ultimate boredom cure. This was, and is, powered by the Internal Combustion Engine, which must have fuel. Methane is a fuel, which means it burns in air to produce energy, but unfortunately it’s a gas; a tank-full would propel a Honda 50 for about half a mile. But! Methane had not been idle since the formation of planet Earth, and had joined up with more carbons and hydrogens to make chains called ‘hydrocarbons’. Well, they weren’t called that at the time. They had to wait for a life-form to evolve that liked giving things names, and a hundred and 20-odd years ago chemists had to learn Latin, so they called the one with five carbons ‘pentane’, the 6-carbon one ‘hexane’, then ‘heptane’ then ….wait for it…. the 8-carbon one ‘octane’ and so on. (If we were naming them now the last one would be called ‘eightane’ so you would need 95 minimum REN for your engine.) All these things were liquids, very thin and volatile, and pure concentrated energy. The Hildebrand and Wolfmuller (rough 1894 equivalent of the Honda 50) now did 100 miles to the tank full.Unlike water, these liquids don’t stand around in lakes. They are hidden underground in porous rock so you have to drill for them. The old name was ‘petroleum’ meaning ‘rock oil’ but this was soon shortened to ‘petrol’. The petrol came out of the wells mixed with heavy oil, so it had to be distilled off in an oil refinery. Early on, the pale coloured stuff that evaporated easily and caught fire very easily was sold as internal combustion engine fuel. It was a simple as that. ‘Octane Number’ hadn’t been invented, but in modern terms this ‘light petroleum fraction’ was about 50 Octane. Now we all know that in the GCSE Science engine The Piston squeezes the air/fuel mixture, then The Spark Plug ignites it to produce The Power Stroke. The trouble is, with 50 octane fuel if The Piston squeezes too much the heat generated by compression makes the stuff Go Bang prematurely before The Spark Plug gets a look in, giving a Power Stroke with as much push as a fairy’s fart. This is why early engines couldn’t use compression ratios above 4 : 1, and 10BHP per litre was seen as hot stuff. Engines improved but petrol didn’t and even some time after WW 1 a touring 1000cc engine only turned out about 25BHP, and a hot-shot Sport version with the latest overhead valves would need a good tuner to get 50BHP.  So finally some effort was made to stop primitive petrol going bang too soon, and a variable compression engine was invented for research. (The ‘CFR’ engine, as used for finding Research and Motor Octane Numbers, RON and MON, to this very day.) Early on researchers found that the bung in the CFR head could be really screwed down if a heavy liquid called ‘TEL’ (tetra ethyl lead) was added. This was really effective and cheap, and allowed the ‘straight’ petrol to be upped to 90 or even 100 octane, and a whole load of exciting high-power engines were designed around these fuels.This leaded fuel survived into the late 1990s, but much earlier an amazing discovery had been made. The shape of the petrol molecules was very important. ‘Octane’ if the ‘straight eight’ version with 8 carbons in a row had an ‘octane number’ of 25. It was only the mutant octane with 5 carbons down the middle and the others sticking out from the sides that gave the best results at high compression. (This special octane is still used as a standard for 100 octane. Proper name is 2,2,4-trimethyl pentane.)Today, ‘petrol’ is really a synthetic fluid built up from oil industry feedstocks. Very little of it is unmodified distillate from crude oil. It is tailor made to include the best compression-resisting molecules so that no poisonous and polluting lead compounds are needed to reach 95 or even 98 octane. Nothing much is added, apart from a touch of detergent to keep the engine top end clean. Quite a lot of petrol now has 5% ‘renewable’ alcohol as a planet-saving gesture, but this also improves the octane number (by about 1 ) so there’s nothing wrong with that. Anyway, if you have a motoring holiday instead of flying ComaJet, you are keeping that carbon footprint down….and paying too much tax as well…..but that’s another story.Fascinating stuff.]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.10'>What do those technical names / bits do?</category>
<author>noauthor@nospam.com (oilman)</author>
<pubDate>Tue, 17 Aug 2010 08:27:34 -0500</pubDate>
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						<title>Engine Oil, what is it and is it worth the money?</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.10.211</link>
<description><![CDATA[We get asked many oil related questions every day and decided to put some of the most frequently asked ones to an Oil Expert called John Rowland. He has been the Chief R&D Chemist for Fuchs/Silkolene for many years and previously developed ahead of their time ester based oils for the RR Jet industry. What he doesn’t know about oil is not worth knowing in our opinion!Even though some of these topics may have been covered before here, this post is well worth reading.1) How is an oil manufactured; transformed from the black sludge that comes out of the ground, into the nectar-like substance we pour into our cars and bikes?Crude oil, which is usually very thin, (contrary to popular belief!) is distilled into light and heavy fractions, with several intermediate ones. (The evil left-overs are used to fuel the 15 million cc/40RPM diesels in the giant oil tankers that bring the crude to the refinery.)The lighter fractions, usually more than 90% of the original crude, are converted into petrol and diesel. Some of the heavier oils, (still dark and smelly!) go through several processes to clean them up and remove wax. Out of about a dozen oily products 4 clear, bright amber oils are commonly used to blend modern engine and gear oils. These are roughly equivalent to SAE 10, 20, and 30 engine rating and 140 gear rating. Oil refineries also produce all sorts of gases and chemical compounds which can be used to build up 'tailor made' lubricants: synthetics! 2) What are the most important substances added to the refined base oils? What do they do?In the Dark Ages, engines used blends of refined mineral oils 'straight', with nothing added. The trouble was, even in the slow-revving engines of 80 years ago the oil didn't last very long, and the engines didn't either. Black sludge and corrosion were the killers, and both were tackled in the 1950s with detergent and antioxidant chemicals. (When I was a lad, I used to visit a mate of my Dad's who rebuilt the very popular side-valve Ford engines. The thick [%*^#@!] inside these things was unbelievable! The valve tappets were moving in holes in solid blocks of carbon!) The detergents washed the carbon from fuel combustion off the bores and out of the ring grooves, and at the same time reduced bore and piston ring corrosion. The antioxidants stopped the oil reacting with oxygen in the air, which cut acid sludge formation which in turn reduced corrosion and oilway blockages. Some antioxidants had the useful side-effect of reducing wear as well. This added up to longer oil and engine life, both improving about three times. (Straight oil had to be changed every 1000miles, and even lightly-stressed engines running on it were ready for a full overhaul at 15-20,000.) OK, I admit there were design and metallurgical improvements, but they needed that vital 'liquid component' to be fully effective. Later came dispersant compounds which held the carbon as tiny particles in the oil which didn't settle out anywhere, and slipped through the oil filter as if it wasn't there.(Solid bits in well-used modern oil are about 1/1000mm across; the pores in an oil filter are at least 15 times bigger.)The other big problem with oil used to be cold starting. It was usual to have SAE 20 Winter or 'W' grades, and SAE 30 or 40 Summer grades, and even the so-called Winter types would defeat the starter in serious cold weather. Unfortunately, oil is very thick when it's cold, and very thin when it's hot. To have an oil thick enough to look after ahard working engine, you had to use a grade which was too thick when it was cold. The answer was (and is) multigrade! What was needed was an oil that behaved like a 20 'W' grade in the cold, but only thinned down to a SAE 40 or 50 when really hot; yes, 20W/50! This can be done by mixing thin oil with thick polymers based on plastics and synthetic rubbers; these don't do much in the cold, but as the oil warms up they unwind and thicken it up to some extent. The oil still thins down, but not as quickly as a polymer-free or monograde type. Multigrades started to catch on around 1960, but these pioneer types were easily ruined by mechanical shear effects, more so in gearboxes than engines. These days the better quality polymers resist shear even in combined engine/transmissions, so it is essential to use good quality shear-resistant types in a gearbox fed by the engine (such as the traditional mini!), which gives its oil a hard time in both engine and gearbox.Incidentally, there are large amounts of these additives and polymers in there, it's not just 'a little bit of this, a little bit of that'! A good quality mineral 10W/40 can be 80% base 20% additive chemistry, and guess which is the expensive ingredient!3) What are the differences, in layman's terms, between mineral, semi-synthetic and fully-synthetic engine oil? (In terms of structure and performance.)Before we get into details, the first thing to realise that there is no chalk and cheese difference between mineral and synthetic based oils. After all, the chemical compounds which make mineral engine oils so much better are themselves synthetic. Synthetic lubricant bases are stepwise improvements on mineral oil, with more desirable properties and fewer undesirable ones. The second important point is that there's no one thing called 'synthetic'! There are several different types of synthetic lubricant, and to say something like: 'the Supergrunt GTI TURBO must have a full synthetic' is meaningless unless the 'expert' explains what sort of synthetic he means. Equally, to imply that dreadful things will happen if the 1970 RV8 is run on anything other than good’ ole mineral oil is ridiculous. It may not need a 2007 synthetic, but it isn't going to come to any harm if the owner uses a 2007 synthetic!The most basic type of synthetic is really a special mineral oil. Known as 'hydrocracked' bases, these are made in oil refineries by putting certain types of mineral fraction through special processing, so they cost more than the usual mineral types but not much more. They are useful because they resist evaporation at high temperatures. Althoughused for years for genuine technical reasons, they are now popular with marketing men because the magic sexy word 'synthetic' can legitimately be printed on the label without spending much on the oil inside the can!Yes, all low-cost 'synthetics' contain anything from a few percent to 20 percent (i.e. 'semi-synthetic') of special mineral oil. Using fairly simple chemical compounds or gases from oil refineries or other sources, it is possible to 'synthesise' or build up tailor-made lubricant molecules which have very desirable characteristics, such as great resistance to cold, heat, evaporation losses or excessive thinning as they get hot. These are the true synthetics, and the two that are used in engine oils are PAOs (poly alpha olefins) and esters. Neither is cheap! PAOs are related to mineral oils, and are the ideal carriers for all the chemical compounds used in mineral oils. Because they do not gel at very low temperatures, all genuine 0W-something oils have to be based on PAOs to pass the 0W test at a sub-arctic -35C. Esters were originally made for jet engine lubricants, and to this day all jet oils are ester-based. Although similar in performance to PAOs, they have a valuable extra trick: they are good lubricants and help to protect metal surfaces. Esters help with transmission and valve train lubrication. 100% fully synthetic oils are actually quite rare, probably because they are very expensive to make, and even more expensive to buy.Even so, an ester/PAO with a very shear stable multigrade polymer is the ultimate oil for high output engines that are worked hard, which means racing.4) How does oil work? What gives it its lubricating properties? How does it 'cling on' to surfaces?A plain bearing such as a main or big end, when spinning fast is 'floating' on a relatively thick film of oil. The metal surfaces literally do not touch. The high velocity drives a wedge of oil between the two surfaces, and the oil film supports the load, just like a water skier skimming over that very thin lubricant, water. But, when the engine slows down and stops the bearing shells drop through the film and touch the crankpins, just as the skier sinks in up to his neck when he lets go of the rope. It is where there is metal to metal contact that lubrication, that is, something to reduce wear and seizure, is needed. On gear teeth, valve components, and piston rings at top or bottom dead centre, there is no high speed rotation to generate 'wedge' support, so the oil films are very thin, and some metal contact is inevitable. Some fluids, even if they look thick and oily, are completely hopeless! Very pure mineral oils, and some synthetics fall into this group. They depend entirely on chemical load-carrying compounds which react with metal at high pressures and temperatures to provide very thin protective films which prevent micro-welds where metal surfaces come into contact.Detergent and antioxidant chemicals often double up as anti-wear agents. The odd ones out are esters. These are attracted to metal by electrostatic forces and cling on when surfaces are forced into contact. 5) What are (or can be) the main differences between oils of the same type, i.e. what's the difference between a 'good' and a 'bad' oil? It all comes down to honesty really.....so beware! A good oil is what it claims to be on the can. 10W/40? Does it really pass the cold test at -25C? Quite a few I've tested do not. There is usually an API spec quoted, such as API SH or SL. These are car-based, and a good basic quality guide. If absent, leave it on the shelf, and avoid lawyer-speak:'meets the requirements of....' or 'recommended (by whom?) for use in....'. Then there is the 'synthetic' minefield! Provided the price hasn't been pushed up by shipping an average oil 5000miles from the West coast of the USA, you get what you pay for. The best performance oils are made in the more developed European countries, but low price buys the cheap 'modified mineral' synthetic and not much of it, with a poor multigrade polymer. As is so often the case, quality follows cost.6) What are the likely consequences of using poor-quality oil?Usually, these are fairly long term, except in racing. Think of the oil as a liquid component, and poor oil as a cheap pattern spare. In a road car long-term reliability and performance retention (i.e. acceleration figures below new spec., fuel and oil consumption above) are the casualties. Particularly in a high performance or racing car,the effects can be more immediate and catastrophic. 7) Some oil companies have run advertising campaigns that imply their products have special, unique qualities. Can these adverts be taken seriously?Yes and no! Generally adverts in magazines are honest, with marketing-speak terms such as ‘Magnatec’ and ‘Electrosyntec’ really being code words for esters, which are particularly beneficial in performance engine oils. No manufacturer has any unique ‘secret’, so it’s all down to providing the best possible blend for the job at the right price, and making it clear that you get what you pay for. I personally think that the importance of shear stability or ‘stay in grade’ is not stressed enough when quality is talked about.What is dodgy though is claiming that a mineral based oil with a few percent of modified mineral (‘hydrocracked’) synthetic is the DB’s and suitable for racing, etc. when it clearly isn’t. Also, there is endless semantic manoeuvring and lawyer-speak around The Magic Word ’synthetic’. For instance, a ‘synthetic’ oil is invariably semi-synthetic (’Ah! We didn’t say it was all synthetic did we?), and, if low priced, invariably the modified mineral type synthetic. It is a sad fact that you get what you pay for, but even so, stick to the reputable UK/European brands, and remember that shipping an oil half way around the world doesn’t automatically make it better than one made in your home town.As for TV advertising…well, does anybody believe it? Due to its huge cost, a TV advertising campaign can significantly raise the cost of specialist items such as oil. Everybody assumes it’s just a few pence per gallon, but it can be pounds per gallon.)Please can you explain the grading system? What is meant by the weight of an oil? What does 10W/40 mean for example?Weight means viscosity, or resistance to flow. Water and paraffin flow very easily, so they are low or light viscosity. Golden syrup or 140 gear oil do not come out of the can so easily, so they are high or heavy viscosity. Especially with oils, temperature is very, very important. An oil which looks ‘heavy’ at 20C will be very ‘light’ at 100C. People sometimes say, ‘I drained the oil when the engine was hot and it ran out like water…’ so I say, ‘Good! It’s supposed to be like that!’ The American Society of Automotive Engineers (SAE) ratings cover cold starts and ‘up and running’ viscosities. There are two sets of standards, the ‘Winter’ (W) ratings, and the 100C standard ratings. (‘W’ does not, repeat not, mean ‘weight’!) So a 10W/40 oil has to pass a 10W cold viscosity test at -25C, and a SAE 40 test at 100C. In an oil lab there will be a refrigerated viscosity measuring device for the ‘W’ tests and another at 100C for the standard SAE tests. There are 6 ‘W’ ratings from the difficult 0W at -35C to the dead easy 25W at -10C, occasionally used in India for example! The whole point of these Winter ratings is to assist cold starts, to get the oil circulating quickly, and to avoid power and fuel wasting drag as the engine warms up. Once it is warmed up, the 100C ratings count. There are 5 of these, 20, 30, 40, 50, and 60 although why anybody bothers with 60 in the 21st Century is a mystery to me! Sorry folks, but I’ve got to get technical. Viscosity is measured in standard units called ‘Centistokes’, names after a Victorian engineer, Sir George Stokes, who used to time ball bearings as they sank through oil. SAE 30 for example is from 9.3 to 12.5 Centistokes, and SAE 40 follows on at 12.5 to 16.3, although most SAE 40 oils are in the middle at about 14. Now this is something most don’t realise: engines do not know what grade of oil they’re running on. They’re not clever enough! So an engine filled with 10W/40 will be running on a viscosity of 14 at 100C, but with a sump temperature of 90C its seeing a viscosity of 18, so as far as the engine is concerned it’s running on SAE 50. Likewise, at 110C, it’s down to 11 Centistokes so it ‘thinks’ it’s on a SAE 30! (Which is preferable.) The lesson is, do not use power and fuel-wasting thick oils in cool climates. A decent 10W/40 or even thinner is perfectly OK unless you’re running a classic with wide clearances and a slow oil pump.Radical race cars use 1300 Suzuki Hyabusas and work them very hard. (Didn’t one take the old Nurburgring absolute record at one point?). They use our high-ester 15W/50, but that’s OK because they see oil temps around 130C! (No problem for the oil or the engine, but they do fit special oil seals.) At 130C the true viscosity is 10cSt, so the engine thinks its on a thin SAE 30, which keeps it happy.8) What is the best type of oil to use in a road car for general use? Is fully synthetic a waste of money?Personally I’d go for a shear-stable part ester synthetic, SAE 10W/40 or 5W/40. The ‘shear-stable’ bit (ie, a decent quality multigrade polymer) is actually more important than the ‘synthetic’ part! If strapped, I’d go for a shear-stable mineral based oil rather than a ‘synthetic’ of dubious stability that’s probably based on modified mineral oil anyway. Unless you’re covering a huge annual mileage, genuine 100% synthetics are probably an extravagance. High mileage long-distance fans can use a light full synthetic and save on fuel and oil changes, and cut overhaul costs if things get to that stage, but more later…..9) What are the main differences between 2 and 4-stroke oil? Why does 2-stroke oil have to be mixed with fuel?2-stroke oil has a very short working life, straight in and out, and it gets burnt. The 2-stroke engine doesn’t have a sump full of oil and the bearings are all rollers, so there’s hardly any oil drag, hence no need for multigrades. Long term stability is obviously not a problem! But, 2-stroke must burn off without leaving any plug-fouling or detonation-initiating deposits. The detergent and anti-wear additives used in 4-stroke oil leave hard white ash behind when they burn, just what you do not need in a 2-stroke. So 2-stroke oils use low-ash detergents and dispersants, and the better types use ester synthetics to act as anti-wear compounds. With current environmental concerns, smoke is a sensitive issue, so most ‘road’ 2-stroke oils are now low smoke, which requires yet another type of synthetic base designed to burn off invisibly. For some rather basic but very high-revving air-cooled racing 2-strokes there’s still some sense in using blends with that marvellous anti-seize liquid, castor oil! Due to crankcase induction and compression, the classical 2-stroke obviously cannot have an oil-filled sump, so the only way to keep an oil film on anything was to add oil to the fuel, or inject oil into the crankcase space where it could mix with the fuel vapour. There are now some engines where the fuel and oil are injected separately, but the oil is still burnt.10) How important is it to change oil regularly? What are the implications of failing to do so?It is only really important to change oil regularly if the engine covers a low annual mileage made up of slow, short runs. This is being cruel to the oil and the engine! The oil, regardless of its quality, gets full of fuel and water vapour, and never gets the chance to evaporate it all off with a long fast run. The consequences are corrosion, ring and bore wear. It is essential to do a change at least once a year, even if the recommended mileage hasn’t been covered. On the other hand, if you eat up the miles on long blasts the engine and its oil will love it, so with a top-quality oil it is OK to cheat a little on oil drain periods.11) Do some types of oil (i.e. fully-synthetic) ‘wear out’ quicker than others? How important are timely oil changes? Can you rely on the frequency suggested by your User Manual?The type of oil that is likely to give trouble after low mileage is a light viscosity type with poor shear stability, either mineral or modified mineral based. (Such as one of the USA ‘fuel economy’ oils for lazy car engines that pushed the Japanese OEMs to bring in their own oil spec.) The important thing is the shear stability; the much hyped ‘synthetic or mineral’ nonsense is a red herring. The oils that will last the longest are the relatively rare 100% genuine synthetic shear stable types, which will easily stand twice the recommended drain period in a high-mileage high performance engine. (So in the long run they aren’t really so expensive.) Just the thing for those touring fiends who pack up and set of for the Transylvanian Alps as soon as the clocks go forward! Of course, User Manual drain recommendations are based on a back-covering ‘worst case’ scenario of low annual mileage on poor quality oil, so they can be regarded as a very safe minimum mileage.In the past, there used to be trouble with heavy carbon deposits and sludge around the engine with early low-detergent oils, but these days almost any oil with a good API specification will keep everything clean for 10 to 15,000 miles, so that’s the least of your worries.12) Does oil have to be warm to do its job properly? Is it important to warm up your engine before using at speed?Yes, it does have to be at least warm, and preferably hot. Most people except the sort with white finger syndrome find metal at 60C too hot to touch, yet 60C is too cold for oil in an engine that’s going flat-out. The best approach is to use a good 5W/40 or even a 10W/40, and take it easy for the first couple of miles, especially in very cold weather. For racing, a really good warm-up is essential, except perhaps with special 0W/20 low-drag race oils. The trouble is, oil pumps are very good at pushing oil out at 60PSI, but unfortunately there is only 14PSI (atmospheric pressure) pushing it in! (Even less in Katmandhu.) So it’s easy for an oil pump to pull voids or pockets of vacuum in the oil if it doesn’t flow fast enough into to uptake. This ‘cavitation’ obviously reduces the amount of oil the pump can deliver. Also, in high-speed bearings the oil can be too thick to keep up with the high rubbing speeds reached in modern engines so the ‘wedge’ or hydrodynamic’ effect breaks down. I know it goes against common sense (whatever that is) but the faster a bearing is turning the thinner the oil should be. (A 4cm. diameter main bearing is rubbing its shells at 56 MPH at 12,000RPM! To avoid cavitation the oil need to be less 10cSt or less, which is SAE 30 if the oil happens to be at 100C, or SAE 40 if its at 110C.)) What is the difference between road and racing oils?The days of incense-like ‘R’ oils for racing only are past, except for classics. At least as far as 4-strokes are concerned, the best synthetic types are ideal for both race and road use. With ultra-precise components, high-pressure pumps and high engine RPM there has been a move to special synthetic low cavitation/low drag oils to release more power with no reliability loss. These can be (and are!) used in road cars, but 0W/20 is not mentioned in the user handbooks, so there is always some warranty risk. Honda is perhaps the only exception!13) How does a high-performance oil allow the motor to produce more power?An engine wastes fuel energy in several ways, and most of them are due to the laws of thermodynamics, which is another way of saying you can’t do much about it. But up to 6% of engine output is lost due to oil drag, made up of pumping losses and viscous drag between moving components. The transmission is included in this. Provided wear and friction are kept down, there are real gains to be made by using a ‘tough’ but low viscosity oil. Surprisingly, frictional losses are low, down at 3% or less even with conventional oils, so there are few gains to be made here.I have actually seen this extra power output on the dyno! A very experienced operator in Peterborough who does a lot of test work for Lord Emap used his own year-old Honda Blackbird, with the first run on his favourite 15W/50 high-ester synthetic. 128BHP. Then we changed to a 5W40 high ester synthetic. (So it wasn’t an unfair comparison with B &amp; Q 15W/50!) This time we saw 131.6BHP with a corresponding torque increase.Finally we went to a new (at that time) 0W/20 special synthetic and 134.4BHP appeared! Even the boss was impressed! Later trials in different race and road engines showed this level of improvement was no fluke, so it really does work; and, with the right chemistry to look after the engine and transmission internals, there’s no down side of increased wear.14) Why do some engines consume oil? Is this a problem?Large air-cooled engines or classics with wide piston clearances, or very highly stressed liquid-cooled engines which flex under load, or which use ultra-light pistons with the minimum number of rings are likely to be oil users. There is little that can be done about it. Unfortunately, burnt oil tends to leave hard deposits in the combustion chambers which can initiate pre-ignition, so more frequent top overhauls are usually necessary. Occasionally, touring engines will use oil for no apparent reason. This is often due to the oil level rising in the crankcase due to air retention, leading to oil loss through the breather. The answer is to move to a lighter grade of oil to improve air release.15) If you need to top up your engine oil, how important is it to use exactly the same brand and type?Not very important at all. Unfortunately, due to ‘[%*^#@!] covering’ reasons we cannot print this advice on the can! Although officially all manufacturers advise against mixing different makes and grades, in fact there is very little chance of any harm being done, even if one is a mineral 20W/50 and the other is a 5W/30 synthetic. Obviously, avoid this if you can, but do not panic if there’s no other alternative. Just don’t mix 2 stroke and 4-stroke oil!16) There are all sorts of additives available which are supposed to improve ordinary oil and reduce friction, improve power output etc. Are they worth a try?Oil is already a very advanced and deeply researched fluid which does not need any ‘enhancement’. There is no secret formula out in the backwoods that the mainstream lubricant chemists do not know about; but there are plenty of half-baked ideas and gullible people out there! These wonder additives are usually 1930s chlorinated paraffins, long obsolete gear oil additives which should have disappeared in the 1950s, but they keep turning up as ‘Xxtrasuperlube ZX3’ with a mark-up of several thousand percent. They actually corrode engine and transmission internals, so they do far more harm than good. Others depend upon the total myth that PTFE powder coats engine internals and reduces friction. It doesn’t do anything or the sort. It just blocks the oil filter. The AA tested one of these overpriced PTFE concoctions (‘Quick 60’ or something) very thoroughly back in the 80s. They stated: ‘This is an expensive way of coating your oil filter’.So there we have it, would just like to thank once again John Rowland (R&D Chemist) for taking the time to provide these answers to questions that we are frequently asked.CheersGuy]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.10'>What do those technical names / bits do?</category>
<author>noauthor@nospam.com (oilman)</author>
<pubDate>Tue, 17 Aug 2010 08:24:53 -0500</pubDate>
<guid isPermaLink="true">http://c4owners.org/plugins/faq/faq.php?0.cat.10.211</guid>
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						<title>C4 HDi Common Rail Pressure Sensor, where is it</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.2.210</link>
<description><![CDATA[Q1. Hi, Can anyone tell me where I can find the common rail pressure sensor in a C4 picasso 1.6 HDi EGS VTR+ Have been looking but without success so far. Q2. Are all the fuel rail sensors in the same position on all C4 picasso models. Mine is a 1.6 HDI. I have the battery and tray out, also, the fuel filter housing moved and the air filter pipes disconnected but I don't see the pressure sensor. Can you confirm for me please. With my car being an EGS, is the gearbox different moving the sensor to another position? Phil wrote ...It's tucked right round the back of the engine - see picture (looking at the back of the engine) below.You need to remove the battery and tray, air filter inlet pipes - also move the fuel filter housing out the way.Yes they are all the same. Follow the metal injector pipes with your hand down the back or the engine, these go to the rail. Then work your hand to the right..... it'll be on the end. There isn't much room at all.. it'll need to be done by feel!407Ron wrote ...The high pressure sensor is directly under the egr valve,the pic was taken with the egr valve removed...you may have a better chance if you try to get to it from the right/under of the egr valve...this pic was taken from a 407 with the same engine....  This is the removal guide of the high pressure sensor connector for a tuningbox i used on a 407 website i'm on..hope it helps.]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.2'>How Can I?</category>
<author>noauthor@nospam.com (Phil)</author>
<pubDate>Fri, 06 Aug 2010 20:21:29 -0500</pubDate>
<guid isPermaLink="true">http://c4owners.org/plugins/faq/faq.php?0.cat.2.210</guid>
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						<title>My doors rattle or have a hollow sound</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.5.209</link>
<description><![CDATA[My brother asked me to post this because he's too idle to do it himself.He mentioned in his "say hello" thread that the front passenger door on his "new" C4 sounds hollow and cheap, instead of the usual C4 thud. The thud of quality.  This is the problem.The channel on the back of the door skin is no longer attached. I'd guess that it's the side impact bar.How do you fix this?We considered Araldite Rapid Steel, polyurethane glue, gap filling foam and even Sticks Like Sh*t.How about hot melt glue?Lots of hot melt glue. About thirteen sticks, in fact.To be honest I lost count.There's also this thing, it looks like part of the crash structure.Two layers of sticky backed foam rubber from Hobbycraft made sure it wouldn't rattle.It still fits, too.Finished.If you ever want to pull the white foam sheet off your door, peel it back at the edge and cut the glue with a sharp knife. You won't need to glue it back on when you've finished, the glue will self-amalgamate back together when you stick it back down.]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.5'>Known issues</category>
<author>noauthor@nospam.com (Irritant)</author>
<pubDate>Sat, 17 Jul 2010 20:38:26 -0500</pubDate>
<guid isPermaLink="true">http://c4owners.org/plugins/faq/faq.php?0.cat.5.209</guid>
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						<title>Find out why a C4 2.0 HDi is surging at low engine revs and low speed or Kangarooing</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.2.208</link>
<description><![CDATA[C4 2.0HDI and it's developed a lack of power/juddering at around the 1800-2500 rev range, it's fine below and above that range.Basically if I'm just cruising at around the 2K rpm mark, the car sort of judders but if I put my foot down it's fine and will run as normal.OrWhen driving at low speeds the car is surging and jerky. No fault showing on dash. Hold it at about 2k revs it'll just drive juddering. Unplug the MAP sensor plug and drive it a few miles and it drives perfectly, plug it back in and its juddering againPhil wrote ...Is it quite a bad judder/ hesitation? Not like a little hiccup?If it's a little hesitation - like a cough and then goes again - I'd say EGR valve fault.If it's quite bad and it does it every time you get to the 2000 revs mark, I'd go for turbo recopy position sensor.Unplugging the MAF puts it into backup mode, that's why the juddering disappears, as it's on a reduced power strategy and probably isn't taking readings from all the sensors.With what you have said, I'd be swinging towards the turbo recopy position sensor - we had a 307 with the same engine with exactly what you describe.No. 8 in the diagram (click to enlarge).]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.2'>How Can I?</category>
<author>noauthor@nospam.com (Phil)</author>
<pubDate>Sun, 11 Jul 2010 20:40:51 -0500</pubDate>
<guid isPermaLink="true">http://c4owners.org/plugins/faq/faq.php?0.cat.2.208</guid>
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						<title>Find out why a C4 cooling fan not coming on.</title>
<link>http://c4owners.org/plugins/faq/faq.php?0.cat.2.207</link>
<description><![CDATA[A fan not coming on could be a few things:Blown fuseLose connectionFaulty sensor - how to check one: ECU faultTrackie wrote ...I was sitting in my c4 1.6hdi 110, the other day. And then the car started beepng and it was telling me to turn the engine off as it is over heating. as the temperture gauge when over the three bars. so i turned the car off for a while.   I have now notice that when i have the air con on, the fan is also keeping the car temperture down, but when i turn of the air con the car then starts to get to hot as the cooling fan doesn't kick in. This is only a problem when the car is ticking over for some time. it's ok when driving.mjcc wrote ...Mine did all that I put a new sensor in and still the fan would not run. So next I slaved the sensor in and put a heat gun on it I could get the fan to run but only on high speed. Next I took the fan control apart and shorted each control terminal to ground as that is hat the ECU does. when shorting slow speed to ground the solenoid clicked but fand did not run. High speed did. Put a new fan control  Pt # 1038CL in and all is good. The reason all the bars flash is that the ECU has commanded the fan to run and it is not. Hope this helps]]></description>
<category domain='http://c4owners.org/plugins/faq/faq.php?0.cat.2'>How Can I?</category>
<pubDate>Sun, 11 Jul 2010 02:18:58 -0500</pubDate>
<guid isPermaLink="true">http://c4owners.org/plugins/faq/faq.php?0.cat.2.207</guid>
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