There’s more to oil than “C3” – Comma Technical Bulletin

There’s more to oil than “C3”

  • ACEA C3 should not be used as a ‘fit all’ product for vehicles with Exhaust After Treatment devices.
  • There are many types of Exhaust After Treatment friendly oils classified by ACEA ‘C’ sequences.
  • ACEA C3 doesn’t always match vehicle manufacturer specification.Charts showing how ACEA C3 performance levels compare to vehicle manufacturers specifications:

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There’s more to oil than “C3”

It’s many years since viscosity alone, or viscosity and base oil type were enough to determine which oil was right for a given vehicle. It was once common-place for a single barrel of 10W-40 to be used for every vehicle that came in for service.

In recent years, the significant increase in vehicles fitted with exhaust after treatment units has resulted in many vehicles requiring so-called ‘low SAPS’ oils. Some technicians may be forgiven for thinking, or may have even been told, that replacing the old single barrel of 10W-40 with a new single barrel of low SAPS “C3” oil is a safe way to stock just one product that can be used in all vehicles. This could not be further from the truth – there is no single oil that can satisfy requirements for all modern vehicles!

Why can’t I just use a ACEA C3 oil in every vehicle?

Ultimately there are four factors which determine whether an oil is right for a vehicle:

  • The viscosity (SAE) – i.e. the oil’s ‘thickness’ over a given temperature range
  • The base oil type – i.e. whether its mineral, semi or fully synthetic
  • The oil industry speci cation – ACEA sequences such as ACEA C3 (or outside of Europe – API (the American Petroleum Institute)).
  • The vehicle manufacturer’s specification – e.g. VW 507 00

    Simply relying on the ‘oil industry code’ might satisfy one requirement of an engine but not the other factors.


Let’s take a look at 2012 VW Passat – a 2.0 TDI (130kW) fitted with an exhaust after treatment unit (Diesel Particulate Filter). You might think that by simply fitting a low SAPS “C3” oil will be safe, but as the diagram shows overleaf, a product that merely meets the requirements of ACEA C3 performs significantly differently versus one that also meets the requirements of the relevant Volkswagen specification.

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