Ford Focus>> System of greasing of the engine>> Engine oil

Oil prevents a dry friction and wear of pistons, cylinders, and also all bearings of a cranked shaft and the klapanny mechanism. Besides, engine oil in addition condenses a gap between the piston and cylinder walls. Oil also assumes cooler function, taking away heat from internal walls and engine details. Besides, it protects from corrosion, holds working off particles in a suspension and connects a part of chemical products of combustion.
Modern engine oils are the lubricant received from refined oil. Producers of oils add to them special additives which make to 20 % from engine oil. Additives, in particular, protect oil from process of oxidation and prevent its foaming on high turns. One of vyazkostno-temperature characteristics is the index of viscosity of VI — it is an empirical, dimensionless indicator for an assessment of dependence of viscosity of oil from temperature. The numerical value of an index of viscosity is higher, the less viscosity of oil depends on temperature. Oil with a high index of viscosity has the best fluidity at low temperatures and higher viscosity at working temperature of the engine. Service life of engine oil is influenced by such factors, as availability of water, quality of fuel and burning products. Therefore regular change of oil is obligatory.
Synthetic engine oil is in most cases more expensive than the mineral. The initial high price is compensated by decrease in a consumption of oil and fuel and increase in an interval between oil replacement.