Understanding motor oil standards
When choosing a motor oil, you can refer to the standards of the product. This information allows you to understand the type of engine the motor oil is designed for (diesel or petrol), its performance level and whether the oil meets your automotive manufacturer’s recommendations.
Here is everything you need to know about the three standards are used to describe motor oils:
The ACEA oil standard
This is the standard of the European Automobile Manufacturers' Association. It is a quality indicator that is determined by a letter and a number (e.g. A1). The letter indicates the type of engine:
- A – oil designed for petrol engines.
- B – oil designed for diesel engines in private cars.
- C – for light engines equipped with catalytic converters or particulate filters.
- E – for commercial vehicles and trucks.
The number indicates the specific performance the oil must provide. The higher the number, the greater the oil’s performance.
The ACEA’s 2016 guidelines define:
- Three category combinations for petrol and diesel engines: A3/B3, A3/B4, A5/B5.
- Five categories for vehicles with a pollution control device: C1, C2, C3, C4, C5.
- Four categories for commercial vehicles and trucks E4, E6, E7, E9, of which two are for vehicles with a pollution control device: E6 and E9.
The SAE oil standard
Determined by the Society of Automotive Engineers, this standard describes the oil’s viscosity.
Marked as follows on the oil container – 00w00 – the number on the left is the low-temperature viscosity. The lower the number, the more efficient the product is at low temperatures.
The number on the right indicates oil performance when hot. The higher the number, the more efficient the oil is when subjected to high temperatures.
The API oil standard
Established by the American Petroleum Institute, this standard classifies the product according to several criteria: dispersive and detergent power, and protection against wear, oxidation and corrosion.
The standard consists of two letters: S for gasoline petrol engines, or C for diesel engines. The second letter indicates the oil’s performance. The further along the alphabet the letter, the higher the quality of the oil. For example, an SH oil will have a lower performance than an SN oil.
To know more about the standard required for your vehicle, check your vehicle owner’s handbook.