Engine Oil with ACEA C2

ACEA C2 is the low-ash performance class with a focus on low friction: for vehicles with a particulate filter whose manufacturer intends a low-friction oil. It is widespread above all at French, Italian and Japanese brands. Whether your engine calls for C2 is shown by the manual or the oil finder.

Which vehicle?

Enter your vehicle - we show only what belongs in it.

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C2 and C3: same ash, different oil film

Both classes are Low SAPS - sulphated ash, phosphorus and sulphur are capped so the particulate filter does not clog. The difference lies in high-temperature viscosity under shear (HTHS):

**C2** allows a thinner oil film and thereby lowers friction losses - the engine has to be built for it
**C3** holds a stronger film and is the most widespread class among German manufacturers

A C2 oil in an engine that calls for C3 is therefore not a harmless swap - the classes are interchangeable only where the manufacturer names both.

Who specifies C2

Typical C2 vehicles come from the PSA group (Peugeot, Citroën, DS, newer Opel and Vauxhall models) with the in-house standard **PSA B71 2290**, from Toyota and Lexus, and from Fiat (standard 9.55535-S1). The in-house number and the ACEA class are usually given together in the manual; if the pack carries the in-house standard, C2 is as a rule the basis.

The class is usual in 0W-30 and 5W-30, increasingly also as a dual C2/C3 approval that meets both sets of requirements at once.

Thinner still: C5 and C6

Where C2 stops, C5 and C6 carry on: HTHS viscosity lowered again, for 0W-20 engines. The direction is the same - less friction, more efficiency - but every step presupposes an engine expressly designed for it. Moving up the ladder on your own initiative is no virtue with oil classes.

Frequently asked questions

Can I use C3 where C2 is specified?

Only if the manufacturer permits both classes. C3 is thicker at operating temperature; the consumption benefit is lost, and on engines with a tightly dimensioned oil pump the thicker class is not intended. The manual decides, not the similarity of the names.

What does PSA B71 2290 mean?

The PSA group's in-house standard for low-ash, low-friction oils - technically built on ACEA C2. If your Peugeot or Citroën calls for this standard, it has to be on the pack; a C2 without the in-house standard is not automatically approved.

Is C2 for petrol or diesel engines?

For both. The C classes describe ash content and oil film, not the fuel type. What matters is that the manufacturer names the class for the specific engine variant - on diesels with a particulate filter it is mandatory, and increasingly so on petrol engines with a petrol particulate filter.