Motor oil specification
The quality of motor oil is indicated by the corresponding standard of car and oil manufacturers.
Motor oils are classified according to the API system: an abbreviation of the first letters of the American Petroleum Institute (american Petroleum Institute). The designation is carried out using two letters.
The first letter indicates the area of application: S - for internal combustion engines, C - for diesel engines.
The second letter indicates the quality of the oil in alphabetical order. The highest quality oils are those of specification SJ for internal combustion engines and CF for diesel engines.
European oil manufacturers use the ACEA (Association des Constructeurs Europeans d'Automobiles) specification, which takes into account European engine production technologies.
Oils for gasoline engines of passenger cars have ACEA classes from A1-98 to AZ-98; diesel engines - classes from B1-98 to B4-98, where 98 is the year the standard was adopted.
The highest quality oils are AZ oils for gasoline engines and VZ oils for diesel engines.
Warning! Motor oils that the manufacturer indicates are intended for diesel engines cannot be used in gasoline engines. However, there are oils that are suitable for both gasoline and diesel engines. In such cases, both specifications are indicated on the motor oil packaging.
All-season oils are intended for engine lubrication, which eliminates the need for seasonal (summer/winter) oil changes.
The basis of all-season oils is a low-viscosity single-season oil, through the addition of so-called "viscosity index improvers", which ensures the stabilization of all-season oils in a hot state.
This ensures that the engine is properly lubricated both when cold and when hot.
SAE designation (Society of Automotive Engineers) indicates the viscosity of the motor oil.
For example, SAE 10W-40 means:
- 10 - viscosity of oil in cold state. The lower this number, the lower the viscosity of the cold motor oil.
- W - means that the oil is suitable for winter operating conditions.
- 40 - viscosity of oil when hot. The higher this number, the higher the viscosity of the hot motor oil.
Also, easy-flowing oils can be used for engine lubrication (low friction oils). We are talking about all-season oils, which contain additives that reduce the coefficient of friction, as a result of which the friction of internal engine parts is reduced. The base of easy-flowing oils is synthetic oil.
Since the application areas of related oils according to SAE classification overlap, short-term temperature fluctuations can be ignored. Mixing oils of different viscosities is permitted if it is necessary to add oil and the ambient temperatures do not correspond to the viscosity class of the oil poured into the engine.
Warning! Lubricating additives of any kind must not be added to either fuel or lubricating oils.
Diesel engines have a so-called circulating lubrication system.
The oil pump draws engine oil from the oil pan through the oil pickup tube with a mesh filter and forces it into the oil filter.
On the pressure side of the oil pump there is an oil pressure relief valve that maintains the required oil pressure. If the oil pressure is too high, the valve opens and some oil can drain back into the oil pan.
Through the pipe in the filter, the filtered oil enters the main channel.
If the filter is clogged, the bypass valve directs unfiltered oil into the main channel, bypassing the oil filter.
From the main channel, oil flows through the outlet channels to the connecting rod bearings of the crankshaft and from there is sprayed onto the piston pins and cylinders.
(Article posted on Internet portal: OpelBook.ru)
At the same time, through the pressure oil line it enters the cylinder head and lubricates the camshaft bearings.
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