or Login >>         
C4 - DS4 Owners :: Forums :: Coupe and Hatch Pre 2011 cars :: C4 The Garage

Basic Oil advice from oilman at Opie Oils

Home   Forum Rules    Forum Help  Conversion Tools
Please Register to enjoy additional Member Benefits
Top Thanked Forum Posts: Today | Week | Month | Year | All time | Most Thanks Given: To member | By user
Author Post
Wed May 12 2010, 09:27am
Member No: #13676
Joined: May 12 2010
Location: Sunny Cornwall / UK
Basic Oil advice from Opie Oils

When it comes to choosing oil for your car, this post may seem like going back to basics but we at OPIE OILS are constantly surprised by the amount of people who do not understand what is written on a bottle of oil and therefore have no idea of what they are buying or using.

This article should help most car owners as a basic guide, for more detailed information you can always contact us at - Click Here - and we will be more than happy to help you.

So, to be blunt about the subject, if a bottle of oil does not contain the following basic information then DO NOT buy it look for something that does!

1) The purpose for which it is intended (i.e. Motor oil, Gear oil, ATF etc)

2) The viscosity (i.e. 10w-40, 5w-30 etc for Motor oils and 80w-90, 75w-90 etc for Gear oils)

3) The specifications that it meets (should contain API and/or ACEA ratings)

4) The OEM Approvals that it carries and the codes (i.e. MB229.5, VW504.00, FORD 913A, BMW LL04 etc)

Ignore the marketing blurb on the label it is in many cases meaningless and we will explain later what statements you should treat with some skepticism.

So, what does the above information mean and why is it important?


All oils are intended for an application and in general are not interchangeable. You would not for example put an Automatic Transmission Oil or a Gear Oil in your engine! It is important to know what the oils intended purpose is.


Most oils on the shelves today are “Multigrades”, which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)

Multigrades were first developed some 50 years ago to avoid the old routine of using a thin oil in winter and a thicker oil in the summer.

In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature.

The lower the “W” number the better the oils cold temperature/cold start performance. I.E. 5w is better than 10w etc

The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100 degC. This is a fixed limit and all oils that end in 40 must achieve these limits.

Once again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC etc. Your handbook will specify whether a 30, 40 or 50 etc is required.


Specifications are important as these indicate the performance of an oil and whether it has met or passed the latest tests or whether the formulation is effectively obsolete or out of date.

There are two specifications that you should look for on any oil bottle and these are API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d’Automobiles) all good oils should contain both of these and an understanding of what they mean is important.


This is the more basic of the two specs as it is split (for passenger cars) into two catagories.

S = Petrol and C = Diesel, most oils carry both petrol (S) and diesel (C) specifications.

The following table shows how up to date the specifications the oil are:


SG - Introduced 1989 has much more active dispersant to combat black sludge.

SH - Introduced 1993 has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability.

SJ - Introduced 1996 has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limits

SL - Introduced 2001, all new engine tests reflective of modern engine designs meeting current emissions standards

SM - Introduced November 2004, improved oxidation resistance, deposit protection and wear protection, also better low temperature performance over the life of the oil compared to previous categories.


All specifications prior to SL are now obsolete and although suitable for some older vehicles are more than 10 years old and do not provide the same level of performance or protection as the more up to date SL and SM specifications, so if you’ve a recent model, don’t bother.


CD - Introduced 1955, international standard for turbo diesel engine oils for many years, uses single cylinder test engine only

CE - Introduced 1984, improved control of oil consumption, oil thickening, piston deposits and wear, uses additional multi cylinder test engines

CF4 - Introduced 1990, further improvements in control of oil consumption and piston deposits, uses low emission test engine

CF - Introduced 1994, modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engines

CF2 - Introduced 1994, defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engines

CG4 - Introduced 1994, development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine tests

CH4 - Introduced 1998, development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuels

CI4 Introduced 2002, developed to meet 2004 emission standards, may be used where EGR ( exhaust gas recirculation ) systems are fitted and with fuel containing up to 0.5 % sulphur. May be used where API CD, CE, CF4, CG4 and CH4 oils are specified.


All specifications prior to CH4 are now obsolete and although suitable for some older vehicles are more than 10 years old and do not provide the same level of performance or protection as the more up to date CH4 & CI4 specifications.

If you want a better more up to date oil specification then look for SL, SM, CH4, CI4


This is the European equivalent of API (US) and is more specific in what the performance of the oil actually is. A = Petrol, B = Diesel and C = Catalyst compatible or low SAPS (Sulphated Ash, Phosphorus and Sulphur). These specs are more commonly found on European oils and in many respects are more important than API for European Manufactured cars.

Unlike API the ACEA specs are split into performance/application catagories as follows:

A1 Fuel economy petrol

A2 Standard performance level (now obsolete)

A3 High performance and/or extended drain

A4 Reserved for future use in certain direct injection engines

A5 Combines A1 fuel economy with A3 performance

B1 Fuel economy diesel

B2 Standard performance level (now obsolete)

B3 High performance and/or extended drain

B4 For direct injection car diesel engines
B5 Combines B1 fuel economy with B3/B4 performance

C1-04 Petrol and Light duty Diesel engines, based on A5/B5-04 low SAPS, two way catalyst compatible.

C2-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible.

C3-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible, higher performance levels due to higher HTHS.

Note: SAPS = Sulphated Ash, Phosphorous and Sulphur.

Put simply, A3/B3, A5/B5 and C3 oils are the better quality, stay in grade performance oils.


Many oils mention various Car Manufacturers on the bottle, the most common in the UK being VW, MB, BMW, Ford or Vauxhall but do not be misled into thinking that you are buying top quality oil because of this.

Oil Companies send their oils to OEM’s for approval however some older specs are easily achieved and can be done so with the cheapest of mineral oils. Newer specifications are always more up to date and better quality/performance than the older ones.

Some of the older OEM specifications are listed here and depending on the performance level of your car are best ignored if you are looking for a quality high performance oil:

VW – 500.00, 501.00 and 505.00

Later specs like 503.00, 503.01, 506.00 are better performing more up to date oils but as far as VW is concerned even these have now been superseded by the latest VW504.00 and VW507.00 specifications.

MB – 229.1, 229.30

Later specs like 229.31, 229.5, and 229.51 are better performing more up to date oils.

BMW – LL98

Later specs like LL01 and the latest LL04 oils are better performing more up to date.


Above is the most accurate guidance we can give without going into too much depth however there is one final piece of advice regarding labelling.

Certain statements are made on labels that are meaningless and just marketing hype; here are a few to avoid!

Recommended for use where……………

May be used where the following specifications apply……………

Approved by………………………..(but with no qualification or specification)

Recommended/Approved by (some famous person, these endorsements are paid for)

Racing/Track formula (but with no supporting evidence)

Also be wary of statements like “synthetic blend” if you are looking for a fully synthetic oil as this will merely be a semi-synthetic.

Like everything in life, you get what you pay for. The cheaper the oil the cheaper the ingredients, lower the performance levels and older the specs it meets so beware!


Guy and the - Click Here - Team
1 User said Thank You to oilman for this Post :
 Gareth Wales (24 May 2013 : 20:45)
Thu Jul 22 2010, 03:53am
so if I was buying 5w-30 fully synthetic Castrol Oil do I want the A1 or A3/B4 (Castrol Magnatec 5W-30 A3/B4 Vauxhall - Opel - Fiat - Renault or Castrol Magnatec 5W-30 A1 Fully Synthetic Engine Oil - Recommended by Ford) for a C4 1.6 petrol?

I am assuming A1 as A3/B4 would be for diesel, correct?

A1 Fuel economy petrol
A3 High performance and/or extended drain
B4 For direct injection car diesel engines
Tue Nov 23 2010, 03:46am
Member No: #11625
Joined: Nov 30 2009
Location: aberdeen
It's worth bearing in mind that Citroen specify oils that are perfectly suitable for year round use under UK climatic conditions. No-one should be using a 10W or 15W multigrade (at least for street use, diesel engines). I.e if the OEM's oil specifications are followed, there is no requirement to change to special winter oils.

It's also knowing that for diesels, the effect of the soot will eventually cause an oil to go out of specification. So if you are the type that only changes oil every couple of years, maybe because of low mileage, reconsider your change frequency and align for the beginning of winter as per the severe operating conditions guide.

Tue Feb 22 2011, 01:00am
One thing I don't get. My wife's car uses 5W-30 oil.
I put in this stuff: Magnatec 5W-30 A1
Now that's semi-synthetic. I wanted to upgrade to the more expensive stuff - the EDGE stuff from Castrol - seems reasonable right as they do 5W-30 in EDGE also.

I queried compatibility on their website with their checker and then asked them about it, as EDGE never came up as recommended and I got a reply similar to what's now in their FAQs:

- Click Here -

Q. I notice EDGE 5W-30 – can I use this for Ford engines?

A. No – Most Ford engines specify a 5W-30 Fuel efficient oil meeting WSS-M2C-913B/C and we recommend the use of Magnatec 5W-30 only. The exceptions are the Galaxy with the VW PD engine, and the latest Ford KA which should have Edge Turbo Diesel 5W-40 (VW 505.01 / FRD 917A specification.) and the latest Focus RS (refer to dealer)

I am not sure what that means. Can anyone explain in layman's terms please? When I got the email reply from Castrol, I think the way they implied was that there was nothing wrong with EDGE, but one of Ford's requirements in their engine oils was price and so EDGE was too expensive to be recommended.


Jump:     Back to top

User Colour Key:
Head Administrator, Administrator, Forum Moderator, Forum Moderator, Premier Member, Technical Expert, New C4 and DS4 Forum Moderators, Member