When choosing a motor oil, pay particular attention to the following parameters:
Oil viscosity
Indicated by a two-number combination in the following format: xxW-yy (eg. 10W-30).
- xxW describes the oil’s lubricating properties in winter temperatures. The lower the number, the better lubrication.
- yy describes the oil’s properties in the summer season. The higher the number, the better it copes with high temperatures.
For example, an oil marked as 5W-30 does better in winter compared to 10W-40, but in hot summer temperatures its lubricating properties are worse.
Recommended SAE viscosity based on outside temperature
Performance class
Motor oil, according to their age divided into performance classes. In Europe, the most commonly used classification ACEA. For their labeling, a combination of the letters A, B, C, and digits 1-5, e.g. A1 / B1 and A3, B3, B4. Information on the correct performance class for your car, see the user manual for the car.
Motor oil performance classes according to ACEA:
- A - Petrol engines
- B - Diesel engines of passenger cars, vans, and light commercial vehicles
- E - Diesel engines of heavy duty vehicles
- C - Petrol and diesel engines fitted with particulate filters
Most widely used oil categories for passenger cars:
| ACEA performance class | Application |
| A1 B1S | Standard oil, normal change intervals |
| A2 B2 | Standard oil, normal change intervals (no longer valid) |
| A3, B3 | Oil for high-performance workloads, can extend change intervals |
| B4 | Same as B3 + can be used for diesel engines with direct injection |
| A4 | Reserved for oils for petrol engines with direct injection |
| A5, B5 | Same as A3/B4, but with reduced HTHS viscosity |
Beware of automaker standards
Some manufacturers, such as Volkswagen, Mercedes-Benz and others, require that the motor oil meet their own company specifications. Always make sure that the engine oil you are buying actually meets those standards.
For Mercedes-Benz, look for a label with specifications such as MB 229.3 or MB 229.5. With Volkswagen cars, it is often VW 506 01 or VW 507 00 (applies to Škoda, Audi, Seat). Once again, you can look up the number in your car’s user manual.
Mineral or synthetic?
While mineral lubricants are made from petroleum products, synthetic oils from are obtained artificially by other means. Synthetic oils are generally considered to be better, with better lubricating properties and longer service life. That said, with modern oils their properties are virtually identical and production process has negligible impact on the viscosity and quality of the oil.
Can I mix oils of different brands?
When adding the oil, make sure the viscosity class matches exactly. If it does, you can mix oils from different brands without any issues.
