13.1. Engine oil
At the choice of engine oil first of all it is necessary to be guided by recommendations and requirements of manufacturer to quality and producer of engine oil.
The modern engine oils consisting of basic oils and the picked-up set of additives are divided into two main types:
– mineral (received by distillation from oil) – their viscosity strongly depends on temperature. Various additives which, in turn, quickly enough collapse because of high mechanical and thermal loadings are applied to stabilization of properties, reducing oil service life;
– synthetic (received by chemical synthesis) – have high uniformity and stability of properties. Remain more liquid on a frost and more dense during a heat, burn down in the engine less, form less deposits, have bigger service life.
Synthetic oils do not destroy engine epiploons, however at their use emergence of a leak through worn-out epiploons owing to the bigger fluidity of synthetic oils in comparison with mineral is possible.
Service life of synthetic oils is only not much more, than mineral. Bystry darkening of oil testifies only to its good washing properties and the polluted lubrication system.
So-called semi-synthetic oils are intermediate. They are made on a mineral basis, but with additives of synthetic components therefore on quality approach synthetic oils, but is much cheaper than them.
One of the main properties of engine oil – its viscosity which determines the temperature range of use of engine oil. At a low temperature of air engine oil has to have low viscosity to provide launch of the engine and intake of engine oil to its knots. At high temperature engine oil has to be more viscous to support the required oil pressure in the lubrication system. On value of viscosity engine oils divide into three look:
– winter – thanks to low viscosity provide launch of the engine and lubricant of the main knots at a negative temperature of air;
– summer – thanks to high viscosity provide lubricant of details of the engine at high temperature of air;
– all-weather – at a low temperature of air have viscosity of winter oils, and at high – viscosity of summer oils.
Use of engine oils is strictly forbidden:
– not intended for petrol automobile engines;
– with inappropriate operational characteristics;
– not corresponding to a season on viscosity (on SAE classifications).