4.1. Specification of engine oil

In modern engines use only of HD oils is allowed. They represent the alloyed oils which lubricant properties are considerably improved at the expense of additive of various chemical biocatalysts. These additives improve protection against corrosion, reduce oxidation, in particular, formation of a deposit in an engine case, is improved by viscosity of oils and their dissolving properties. The clearing and dissolving additives not only reduce formation of deposits in the engine, but also dissolve these deposits, make small all other mechanical impurity in engine oil and support them in suspension so they leave when replacing oil.

Quality of HD engine oils is estimated according to the API system (API – the American Petroleum Institute). The European manufacturers are also guided by this system.

Oils are designated by two letters. The first letter in designation – a scope: S – service, it is suitable for carburetor engines; With – commercial, is suitable for diesel engines. The second letter means quality in alphabetical order. The highest quality according to the API specification: SG – for petrol engines and CF – for diesel.


Engine oils which are marked by the manufacturer as oils for diesel engines are unsuitable for petrol. There are such oils which are suitable both for petrol, and for diesel engines. In this case on a container for oil both specifications are designated (for example, SG/CE).