Engine oil ACEA specifications and what they mean.

[oilman]

When you look in your handbook it will list a bunch of specifications and viscosities that can be used on your car and these are usually API (American petroleum institute) or ACEA specs, often these specs are not explained and can be confusing. Hopefully this post will help explain what they all mean.

ACEA Specifications are also on the back of just about every bottle of engine oil oil sold in Europe, if they’re not then it may be wise to look for something else as they’re there for your protection.

Here is an explanation of what they mean.

A = Petrol

A1
Category for low-viscosity engine oils with particularly low High Temperature High Shear viscosity (< 3.5 mPas). Recommended viscosity grades are XW-30 and XW-20. A reduction in fuel consumption of = 2.5% compared to a 15W-40 reference oil must be proven in a Mercedes M 111 test engine.

A2
Category for conventional and low-viscosity engine oils.

A3
Category for conventional and low-viscosity engine oils with greater demands than ACEA A2. Out-performs ACEA A2 with regard to Noack (evaporation losses), piston cleanliness and oxidation stability.

A5 Testing as for ACEA A3 but with proven reduction in fuel consumption and lower HTHS viscosity. In essence a combination of A3 and A1.

B = Diesel (Light duty diesel engines)

B1
Category for low-viscosity engine oils with particularly low High Temperature High Shear viscosity (corresponds to ACEA A1). A reduction in fuel consumption of = 2.5% compared to a 15W-40 reference oil must be proven in a Mercedes M 111 test engine.

B2
Category for conventional and low-viscosity engine oils.

B3
Category for conventional and low-viscosity engine oils. Out-performs ACEA B2 with regard to cam wear, piston cleanliness and viscosity stability in high soot conditions.

B4
Category for TDI diesel engines. Performance as for ACEA B3.

B5
Testing as for ACEA B4 but with lower HTHS and proven reduction in fuel consumption.

New ACEA specifications were introduced in November 2004 and these will apply in combination for both Petrol and (light duty) diesel engines.

A1/B1
Category for Fuel Economy engine oils with especially low High Temperature High Shear viscosity. HTHS of 2.6 to 3.5 mPas applies to XW-20, 2.9 to 3.5 mPas for all others. Corresponds to the old A1 and B1 specifications with some new engine tests.

A2/B2
Basic requirements. Will be replaced by the GLOBAL DLD-1 specification.

A3/B3
Category for high-performance and Fuel Economy engine oils. Exceeds ACEA A1/B1 with regard to Noack (evaporation losses), piston cleanliness and oxidation stability. Extended oil change intervals possible.

A3/B4
Same as A3/B3 but also for direct injection diesel engines.

A5/B5
Category for high-performance engine oils. For TDI engines with Fuel Economy Performance. In addition with lowered HTHS (2.9 to 3.5). Extended oil change intervals possible.

C = Engines LOW SAPS

This category covers applications where sulphate ash, phosphorous and sulphur content (SAPS) is limited by the OEM.

C1
Largely based on the ACEA A5/B5. Strict limitation of SAPS content. Low HTHS viscosity of >2.9 mPas.

C2
Same as C1 but with somewhat higher SAPS content permissible (as with C3).

C3
Same as C2 except for HTHS > 3.5 and without Fuel Economy performance.

C4
Same SAPS content as C3, HTHS viscosity as C1.

These specifications are often mentioned in your handbook along with a viscosity eg. 5w-40, 5w-30, 10w-40 etc.

Hopefully this is a useful guide until they issue new specs.

Cheers

Guy