BY: Simon Michell, Lubrication expert and freelance industry consultant at Unquenchable 

Engine oils for modern cars are a nightmare”…..they don’t have to be

But get the oil wrong on modern cars and it will come back and bite you

Can you identify the correct oil every time?

Is there a simple way of making sense of modern oils, without having a degree in Tribology? You will be please to know the answer is yes! Use the ‘four level’ approach and engine oil confusion will disappear before your eyes. I have used the 4 level approach in my oil training with motor factors and independent garages …it works every time. Whether it’s for in-warranty or out of warranty cars.


It used to be so straightforward back in the day. We had 20W-50 in the 1970s, 10W-40 in the 1980s and in the early 2000 along came the 5W-30 semi synthetic and fully synthetic oils, so what has changed?

The simple answer is manufacturer specifications.

The question that often asked is why the car manufacturers have created these oil specifications?  The car manufacturers will rightly say it due to the technological advancements that are specific to the engine, emission regulations and the drive for fuel economy

Cynics may suggest it’s a way of encouraging the owner to return to the main dealer, clutching the owner’s handbook, asking for oil that is stated in the handbook. I’m sure you have your own view. Either way. As an independent garage, if you supply the wrong specification oil for a car under warranty, you potentially have big expense coming your way. 

Being curious and keeping up to date about engine technological advances is part of running a successful garage business – Oil is now very much part of that technological advance


The oil registration look up sites are easy to use and accurate. What the 4 level approach does is simplifies the logic and reasoning for different oil recommendations. Follow the four logical steps – and be reassured that you won’t have a warranty claim rejected due to the wrong specifications being used. Additionally you will have the confidence in your oil knowledge to challenge any judgements.


Level one and two are sort of obvious. It’s levels three and four that things liven up


Level 1

The first question to ask yourself is: Is the oil Mineral Semi Synthetic or Fully Synthetic?

All modern oils are Fully Synthetic and this will be stated on the specification sheet.


A few years ago, things were not so clear, with semi synthetic and fully synthetic jostling for attention. Take for example the Ford semi synthetic 5W-30 and the Ford fully synthetic. Thankfully technology has moved on from those days.


Level 2

The next question is: What is the viscosity? While it is easy to find information on the bottle, things have changed in the last couple of years. An example being Mercedes Benz and BMW. In the past they allowed a couple of viscosities with their specifications of MB 229.51 and BMW LL-04. Car manufacturers now tend to stipulate one viscosity to go with their specifications.


Viscosity is the most important feature about oil. Right? – Maybe not, viscosity has an important role to play – but it’s not the only criteria in modern engine oils. As an aside, the viscosity term we are familiar with, as an example 5W-30, is what is known as the Kinematic viscosity. 

There are two other viscosity you will come across with engine oil. Firstly the dynamic viscosity which is used to determine the cold start standard. The second is the High Temperature High Shear viscosity. This viscosity is very much at the forefront of the oil chemists’ minds, when they are formulating the recently introduced fuel economy oils , although this is another topic for another day!


Level 3

This is where things get interesting…the ACEA or ILSAC specification. So what is ACEA? The European Automobile Manufacturers’ Association (ACEA) represents the 16 major Europe-based car, van, truck and bus makers. 

ILSAC, which stands for International Lubricant Standardisation and Approval Committee is an organisation through which Ford, General Motors, Chrysler and the Japan Automobile Manufacturers Association, Inc develop minimum performance standards for passenger car engine oils used in petrol fuelled engines. 


All engine oil sold in Europe will have an ACEA or ILSAC standard. If it doesn’t. Don’t buy it! The oil watchdog VLS would have something to say about oil sold in the UK without an ACEA or ILSAC standard. 

Back to ACEA: Typical designations you will come across will be the Low SAPS oils C1, C2, C3, C4, C5 There are others, but these are the popular Low SAPS – Low Sulphated Ash Phosphorous Sulphur oils, designed for cars with Diesel Particulate Filters (DPF) and Gasoline Particulate Filters (GPF)


There is often a curved ball in oil, and here comes one of those. The oil may only have an ILSAC classification and no ACEA specification.

That’s OK, The oil is simply so new that ACEA haven’t got round to giving it an ACEA classification. The 0W-16 fuel economy oils may only have an ILSAC specification on the bottle. Oh and there is a 0W-8 on its way. Super fuel economy oil


There are three ILSAC specifications that are worth being aware of, because they are relevant for modern petrol engine oils.

  • ILSAC GF-5 Usually found alongside the GM Dexos1 specification. Oils             that are formulated for Low Speed Pre Ignition issues
  • ILSAC GF-6-A Some 5W-20 and 0W-20 oils
  • ILSAC GL6-B  Only 0W-16 oils


Level 4

This is where the manufacturer warranty rejects usually occur

Or put another way. The car manufacturer warranty department is only interested in the correct level four specification. The previous levels may be correct. But it’s a definite reject if this level is incorrect.


Back in the day when we used 20W-50 and 10W-40 – there was limited or no level 3 or 4 specification. 

The oil was Level 1: mineral or semi synthetic – and Level 2: 20W-50 or 10W-40

Not any longer:


An example of two typical modern oils are the Ford and Peugeot Citroen 0W-30 oil specifications

Two deceptively similar, but different level 4 specification oils


Using the 4 level process:

Level 1 Both Fully Synthetic

Level 2 Both 0W-30

Level 3 Both ACEA C2

Level 4 Different specifications Ford WSS-M2C 950-A PSA B71 2312


Ford or PSA are not interested in Level 1,2,3 – (They have formulated their oils to incorporate the important parts of level 1,2,3)

However they are very interested that the correct level 4 oil specification is used.


A quick glance at the Valvoline specification sheet for the Ford and PSA 0W-30, gives us the 4 levels of information we need


Ford 0W-30 Ford 0W-30

Ford 0W-30 Ford 0W-30

Level 1 Full Synthetic

Level 2 0W-30

Level 3 ACEA C2

Level 4 Ford WSS-M2C 950-A


Peugeot Citroen 0W-30


……Don’t confuse the Ford 0W-30 oil with the Peugeot Citroen 0W-30

Level 1 Full Synthetic

Level 2 0W-30

Level 3 ACEA C2

Level 4 PSA B171 2312


……And these two modern 0W-30 oils are definitely not too confused with the 0W-30 that Volvo stipulated way back in the early 1990s

The only level that is correct in this ancient oil is the Level 2: 0W-30!

Volvo 0W-30 from the early 1990s

Level 1 Usually Semi Synthetic

Level 2 0W-30

Level 3 ACEA A5/B5

Level 4 No level 4 specification (or so old that it’s not relevant)


I know from experience that this oil has inadvertently been used instead of the correct Ford / PSA oil!


Below are examples of current manufacturer specifications


Manufacturer specifications

For guidance only – always check the manufacturer lookup





Ford WSS M2C 913 -A/B/C


WSS M2C-913 – D


WSS M2C-948-B

 Ecoboost 5W-20

WSS M2C-950-A 


WSS M2C-934-A

ACEA C1 5W-30

Fiat 9.55535-M2 9.55535-N2 9.55535-GS1
9.55535-S1 9.55535-S2 9.55535-DS1
Land Rover STJLR 03.5003


STJLR 03.5004


STJLR 03.5005

5W-30 C1

STJLR 03.5006


STJLR 03.5007

0W-30 C2

STJLR 51.5122

0W-20 C5

Mercedes Benz MB 229.52 MB 229.51 MB 228.51
MB 229.71 

0W-20 C5

Peugeot Citroen B71 2290


B71 2312 


Porsche A40

0W-40 or 5W-40


Diesel Engines



Renault RN0700 RN0710 RN0720 


VAG VAG 504/507 VAG 508/509 VW 505.01
Vauxhall GM Dexos2 GM dexos1™ Gen 2
Volvo A5/B5 




ACEA Specifications A3/B4



C1, C2, C3, C4, C5



Low SAPS E6, E9

JASO Motorcycle MA MA2 MB


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  1. Having had to deal with an (out of warranty) Citroen that had no oil showing on the dipstick but was apparently running fine & showed no warning oil light, I could not find a local supplier of any 0W-30 C1/C2 at all, let alone Citroen spec. I used some 5W-30 I had, on the principal that some, or even any (fully synthetic) oil was better than a wrecked engine. The car has run perfectly well since, now back on correct 0W-30. Playing Devils Advocate; I am sure car makers have tweaked their oil requirements in tiny ways to suit their specific engine designs but, & I believe it is a big but, All engines will work with almost any oil rather than none! The tiny materials differences between makers are not crucial; 99.99% of us are not driving highly tuned racing cars. A more relevant issue would perhaps be compatibility with DPF or Catalytic converters. So if you are stuck without the correct oil then at least use one that is as close as possible on that front & if you are nervous about it then replace asap with correct oil when you can. Clearly if the car is under warranty then only the correct grade is acceptable, which means your car may be stuck on your drive until you can get some

  2. This is actually really helpful, thanks for the breakdown into four levels, without that it is tempting to choose oil like wine and go for a pretty label and origin over technical suitability.