3.8. Lubrication system
| Petrol engines And – all-weather light oils with the increased antifrictional properties, the VW-500 00 specification In – all-weather oils, the VW-501 01 specification, or the API-SF or SG specification | Turbodiesel In – all-weather oils, the VW-505 00 specification |
Viscosity of oil
Viscosity characterizes oil fluidity. Depending on temperature oil tends to reduction of fluidity. In process of increase in temperature oil becomes more fluid. It worsens adhesion of oil and resistance to high pressure. When cooling oil gets denser, fluidity decreases and internal friction increases. Because of this property it is necessary to apply motive oil with such viscosity which changes at change of temperature in perhaps smaller limits.
At start of the cold engine oil has to be sufficiently liquid excessively not to overload the engine and that after start oil got quicker into all places where lubricant is necessary.
The fluidity of oil is equivalent to its internal friction and is designated by SAE units (Society of Automotive Engineers – Association of Automobile Engineers), for example SAE 30, SAE 10. The high rate of SAE means that oil dense, low – characterizes liquid oil. Nevertheless, viscosity of oil completely does not characterize lubricant properties of oil.
All-weather oils
In engines of the Audi A3 cars all-weather oils are used. Advantage of all-weather oils consists that they do not need to be chosen seasonally. They are made on the basis of liquid seasonal oil (type 10W). In a heated state this oil is condensed by the so-called "stabilizer of viscosity" that provides the corresponding lubricant qualities of oil at all temperatures. When using all-weather oil it is necessary to apply modern grades with a wide temperature range of viscosity, for example 10W–40, 15W–50.
10 viscosity of oil in a cold state. Than the number, especially liquid oil in a cold state is less.
W (winter – winter) oil is suitable for application in the winter
40 viscosity of oil in a hot state. Than the number, especially dense oil in a hot state is more.
Also light oils can be applied (oils to high capacities). They represent all-weather oils into which as additive along with others umenshitel of coefficient of friction are entered. In light oils as a basis so-called synthetic oils are applied.
Classes of viscosity and range of operational temperatures of oil
As the range of use of the next classes SAE are blocked, it is possible not to pay attention to short-term temperature fluctuations. Mixing of oils of various classes of viscosity is allowed if the oil dolivka is required, and surrounding temperature does not correspond to the class of viscosity of oil which is filled in in the engine any more.
ATTENTION
Quality of motive oil
For modern engines it is necessary to use only HD oils. HD oils are oils with the increased lubricant properties improved at the expense of various additives. These additives provide the best anticorrosive protection, more favorable conditions against the oxidation phenomenon, the smallest tendency to formation of slags, the best change of viscosity clearing and dissolving properties. The clearing and dissolving additives not only reduce formation of the remains in the engine, but also at the same time these remains and all other pollution in motive oil have ability to dissolve and keep in suspension so that when replacing oil these pollution are removed together with the merged oil.
Quality of HD oils is determined by the API system (American Petroleum Institut). The European producers also adhere to this system.
Designation of a grade of oil is made by two letters. The first letter characterizes a scope: S-Service, are intended for carburetor engines; With – Commercial, are intended for diesel engines.
The second letter defines an oil grade in alphabetical order.
Premium oils on classification of API are SJ for petrol engines and CF for diesel engines.
The European manufacturers classify the oils under the ACEA specification (Association des Constucteurs Europeens de I'Automobile) which considers, first of all, the European production technology of engines. Oils for petrol engines of cars have according to the ACEA specification quality classes from A1-96 on A3-96, diesel engines have classes from B1-96 on B3-96, and A3 and B3 represent the highest class of quality.
Since 2000 release (MJ00) within extension of intervals of service (Long–Live–Service), and also new norms on motive VW/AUDI oil are applied to the engine of 154 kW in the AUDI S3 cars.
If the required oil is absent, on cars without Long–Live–Service with petrol engines motive oil according to ACEA-A2/A3 or API-SF/SG can temporarily be applied. On a turbodiesel in this case oil of the API-CD specification can be applied.