Buying guide for engine oil – increase engine life and performance

Engine oil is essential for engine performance and longevity. Without engine oil, the engine would be destroyed in seconds. The main task of engine oil is to lubricate the metal parts of the engine and keep the friction surfaces in the engine apart. It also helps cool the engine, prevent corrosion and keep it clean. But it also reduces vibrations and therefore dampens the engine noise. What should you consider when buying engine oil?

Before you buy engine oil

Before buying engine oil, you should look to see what the manufacturer of the car recommends. This information can be found in the car's manual. There you will find, among other things, which oil type and viscosity grade you should use, as well as which specifications it should have. The specifications are important for getting an engine oil with the right type of additives and which is designed for your car

Different types of engine oil

Mineral oils

Engine oil is an oil that basically consists of a base oil and a number of additives. The base oil can consist of petroleum, synthetic substances or a combination of the two. Base oil petroleum is refined from crude oil, which consists of substances such as sulphur, nitrogen, oxygen and various metal components. Since these substances cannot be completely removed in the refining process, they remain in the petroleum. Petroleum-based engine oil is usually called mineral oil.

Synthetic oil

Synthetic oils are also produced from crude oil but are produced unlike petroleum-based oil with more advanced processing processes. This means that the oil is modified at the molecular level and that more impurities can be removed from the crude oil. This makes the synthetic base oil cleaner and more stable. The advanced refining process also makes it possible to tailor the base oil to better meet the needs of modern engines. The versatility and molecular structure of synthetic base oil provide better friction reduction, optimal fuel efficiency and temperature performance.

Semi-synthetic oil

Semi-synthetic oil, as the name implies, consists of a mixture of mineral oil and synthetic oil. In this way, the properties of the engine oil can be adjusted to some extent. Its properties can be customised more than mineral oil but not as much as the synthetic oil.

Viscosity of engine oil

Viscosity means how viscous the engine oil is at cold start and how fluid it is when the engine is hot. The viscosity grade of the oil is indicated on the basis of the SAE system, which consists of a number of winter and summer classes, for example, 0W, 5W, 10W, 15W (winter) and 20, 30, 40, 50, 60 (summer). There are also combined summer and winter oils (5W-40). The higher the figure, the thicker the oil. Which viscosity grade is best for your car engine? The answer to that question can be found in the car's owner's manual. If you use the wrong oil, there is a risk that lubrication will not be optimal, which in turn causes the engine to be subjected to excessive wear.

Engine oil quality class

This is where it gets a little harder. To put it bluntly, there are two big and a number of small quality rating systems. The two major systems are the API system and the ACEA system. The API system consists of an S-code (for petrol engines) and a C-code (for diesel engines), as well as a letter. The further into the alphabet that letter number two is, the higher the quality. The ACEA system has other codes. Codes A3/B3/B4 are the highest (A is for gasoline engines and B for diesel engines). A2/B2 is a simpler type. A1/B1 and A5/B5, on the other hand, indicate that oil is a fuel-saving variant.


There are currently three general organisations that administer classification systems for motor oils API, ILSAC and ACEA.

API - American Petroleum Institute. API administers licenses and certifications for engine oils according to a system that meets the requirements set by vehicle manufacturers for warranties, maintenance and lubrication. API also administers ILSAC licenses issued to the oil companies.

ILSAC - the International Lubricants Standardisation and Approval Committee, formed in 1992 by AAMA (American Automobile Manufacturers Association) is the representative of DaimlerChrysler Corporation, Ford Motor Company, General Motors Corporation and JAMA (Japan Automobile Manufacturers Association) to define the need, parameters, licensing and administration of the lubricant specifications.

ACEA - The European Automobile Manufacturers Association regulates the requirements and wishes of European car manufacturers.

Keep in mind...

When changing the oil in your car, the old oil is considered hazardous waste and must be handed in to a recycling centre or at businesses and stores that accept waste oil. We recommend pouring the old oil into the new oil container when empty.
Before recycling waste oil, we advise you to check which local rules and guidelines must be followed when recycling hazardous waste.

Frequently asked questions about engine oil

Can you mix different engine oils?

Yes. You can mix any engine oil, regardless of whether it is mineral, semi-synthetic or synthetic. But the properties and quality of the oil are affected. 

Can the engine be damaged by the wrong engine oil?

Yes, using the wrong oil can lead to increased wear or engine damage.

How do I find out what is the right engine oil for my car?

The car's manual states which engine oil the car manufacturer recommends. If you feel unsure, you are always welcome to speak to us at Biltema.

What do the numbers on the engine oil mean?

The numbers indicate the viscosity and quality class of the engine oil.