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The basics of lubricants: ACEA specifications for passenger cars (3/9)

You may know the ACEA oil sequences. But can you tell what separates ACEA A3 from ACEA B4? Educate yourself here.

Technical Expertise

In our series about the basics of lubricants, we now dive into the ACEA oil sequences for passenger cars. These sequences are a series of oil specifications.

What's a specification? Engine oil has to meet certain technical standards. To that end, associations of manufacturers have defined 'specifications'. Each specification is associated with a number of tests that indicate the quality and the performance of a lubricant.

Only when a lubricant makes it through all the tests, the lubricant producer can claim that it has 'specification X' and can be used with certain engines without risk (as defined in the specification).

Let's take a look at ACEA and their latest specifications, specifically.

What is ACEA and what does it do?

ACEA was founded in 1991. It’s an abbreviation of Association de Constructeurs Européens d’Automobiles, or in English: European Automobile Manufacturers' Association.

In short, ACEA is an advocate for the automobile industry in Europe. They represent manufacturers of passenger cars, vans, trucks and buses with production sites in the European Union.

Members of the Association include the national associations for the automobile industries, plus most of the car, van and truck manufacturers.
170802 - Basics of lubricants - PC ACEA logo

The European Oil Sequences

High-quality lubricants are necessary to ensure the reliability of modern high-tech engines. And there is no single best oil: Different oils are required for different circumstances, engine designs, and climatic conditions.

With its European Oil Sequences, ACEA provides minimum standards for oils. These are the standards that ACEA members demand for using these oils in their vehicles, and are also called specifications.

How to read an ACEA specification

Every ACEA specification is made of a letter and a number. The letter indicates the class and the number indicates the category:


C indicates the class; 3 indicates the category. 
Here, one element can get a little confusing. There are three ACEA classes: ACEA A/B, ACEA C and ACEA E. 
The thing to note here is that you won't find ACEA A (without the B) or ACEA B (without the A). 
It's always A/B. An ACEA A/B specification looks like this:


A/B indicates the class; 3 indicates the category. 
Finally, specifications can show their year of implementation. 
This is done by adding the last two numbers of the year. For example:

ACEA C1-16

C indicates the class, 1 indicates the category, and 16 indicates the implementation year (2016).

About the ACEA classes and categories

The three classes divide ACEA specifications by general application:
  • A/B class: This specification applies to passenger car motor oils
  • C class: For catalyst compatible motor oils

The categories, indicated by numbers, divide them according to requirements for different engines.

The ACEA specifications you need to know

Here are ACEA's current specifications as defined in their 2016 oil sequence. Important note: Some oils are unsuitable for use in certain engines — always consult your original owner’s manual/handbook to find the right specification for your vehicle.


Stable engine oil for use in passenger cars together with light duty van gasoline and diesel engines. It is stay-in-grade, meaning the viscosity stays the same under different conditions. (The viscosity is the 'thickness' of oil, which is preferred to stay constant even in hot or cold conditions.)


Very similar to ACEA A3/B3, this specification allows for slightly more anti-wear additives. This makes it more suitable for high-speed direct-injection diesel engines.


For use in passenger cars together with light duty van gasoline and diesel engines capable of using low-viscosity oils.

ACEA C1 Stable, stay-in-grade engine oil for use as catalyst compatible oil in:
  • Vehicles with all types of modern after-treatment systems
  • High-performance passenger cars
  • Light-duty van gasoline and direct-inject diesel engines capable of using low viscosity (‘thin’) oils

Similar to ACEA C1, but for oils with a Mid SAPS level (= that contain medium levels of environmentally polluting metals).


Similar to ACEA C2, but for engines that can use specific low viscosity oils.


Similar to ACEA C3, but for oils that contain low levels of environmentally polluting metals.


Also similar to ACEA C3, but for engines that can use even lower (‘thinner’) viscosity oils. ACEA C5 oils also provide more fuel economy.

How to choose the right ACEA specification

As you'll have guessed, the different classes and categories each have their own application. Using oil with the incorrect specification can not only diminish your engine's performance, but could even damage it.

Always refer to your car manual for the right ACEA specification.

In short:
  • ACEA is the European Automobile Manufacturers' Association.
  • With its European Oil Sequences, ACEA provides minimum standards for oils.
  • Every ACEA specification is made of a letter and a number.
  • The three classes divide ACEA specifications by general application.
  • The categories divide them according to requirements for different engines.

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