The ACEA classifies oils into three main groups – A/B for petrol (A) and light-duty diesel (B) engines, C for catalyst-compatible oils used in light-duty vehicles, and E for heavy-duty diesel engines. Here’s a breakdown of each classification:

A/B Classifications

The A/B groups specify the oil standards for petrol and diesel engines, primarily used in passenger cars and light commercial vehicles. The classifications range from A1/B1 to A7/B7, with each category catering to different engine designs and capabilities.

For example, A3/B3 classification refers to stable, stay-in-grade oils designed for high-performance engines and extended drain intervals. On the other hand, A7/B7 oils are formulated for use at extended drain intervals in passenger cars and light-duty petrol & DI diesel engines. They provide low-speed pre-ignition and wear protection for turbocharged petrol DI engines and turbocharger compressor deposit (TCCD) protection for modern DI diesel engines.

C Classifications

The C group is designed for catalyst-compatible oils usually used in light-duty vehicles with emission control systems such as Three-Way Catalysts (TWC) and Diesel Particulate Filters (DPF). These oils are Low to Mid-SAPS (Sulphated Ash, Phosphorous, and Sulphur), indicating that they have lower concentrations of these elements to prevent catalyst poisoning and particulate filter blocking.

For instance, C2 oils are stay-in-grade oils for vehicles fitted with DPFs & TWCs, designed for high-performance engines requiring low friction, low viscosity, and mid-SAPS oils.

E Classifications

The E group caters to heavy-duty diesel engines. These oils, ranging from E2 to E9, are designed for use in various diesel engines in severe heavy-duty service and extended drain intervals. They’re compatible with emission requirements such as Euro 3, Euro 4, Euro 5, and Euro 6.

For example, E4 oils are stable, stay-in-grade oils designed for significantly extended drain intervals, suitable for Euro 3, Euro 4 & Euro 5 engine emission requirements. They are typically synthetic or predominantly synthetic.

While the ACEA provides the fundamental standards, some manufacturers also have their specifications, like Mercedes Benz with MB 229.31/229.51/229.52, BMW Longlife-04, and VW 507 00.