Auto Manual of VW Passat B5

2.7.6. The general recommendations about engine oils

THE GENERAL DATA

Viscosity of oil

Viscosity of engine oils


Viscosity characterises fluidity of oil. Depending on temperature oil tends to fluidity reduction. In process of increase in temperature oil becomes more fluid. It worsens ability of oil to сцепляемости and stability to maintain high contact pressure. At cooling oil gets denser, fluidity decreases and the internal friction increases. Because of this property it is necessary to apply engine oil with such viscosity which varies at change of temperature in probably smaller limits.

At start of the cold engine oil should be sufficiently liquid excessively not to overload the engine and that after start oil has fast got into all places where greasing is necessary.

Fluidity of oil is equivalent to its internal friction and is designated by units SAE (Society of Automotive Engineers - Association of Automobile Engineers), for example SAE 30, SAE 10. High indicator SAE means that oil dense, low – characterises liquid oil. Nevertheless, viscosity of oil completely does not characterise lubricant properties of oil.

All-weather oils

In engines of cars it is preferable to use all-weather oils. Advantage of all-weather oils consists that they do not need to be chosen seasonally. They изготавли ваются on the basis of liquid one-seasonal oil (type 10W). In нагретом a condition this oil is stabilised by a so-called thickener that provides corresponding lubricant qualities of oil at all temperatures. At use of all-weather oil, it is necessary to apply modern grades with a wide temperature range of viscosity, for example 10W-40, 15W-50.

Letter W (winter – winter) in designation SAE characterises suitability of use of oil during the winter period.

Classes of viscosity and range of use of oil

As a range of use of 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 if it is required доливка oils is supposed, and the surrounding temperature any more does not correspond to a class of viscosity of oil filled in in the engine.

At long external temperatures more low–20 With it is recommended to fill in oil SAE 5W-20.

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The prevention

Engine oils of CD which the manufacturer designates as oil for diesel engines, are unsuitable for petrol engines. There are the oils which application is possible in two types of engines, in this case both designations, for example SG/CD are specified in capacities with oil.

Additional additives to oil, irrespective of their kind and appointment, should not be added in oil.

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Engine oils

For modern engines it is necessary to use only oils D. Oils HD are oils with the raised lubricant properties improved at the expense of various additives. These additives provide the best anticorrosive protection, more favorable conditions against the oxidation phenomenon, the least propensity to formation of slags, the best change of the viscosity, clearing and dissolving properties. Clearing and dissolving additives not only reduce formation of the rests in the engine, but also ability these rests and all other pollution in engine oil simultaneously possess to dissolve and hold in a suspension so that at oil replacement these pollution leave together with merged oil.

Quality of oils HD is defined on system API (American Petroleum Institut). The European manufacturers also adhere to this system.

The designation of a grade of oil is made by two letters. The first letter характери зует a scope: S – Servise, are intended for carburettor engines; With – Commercial, are intended for diesel engines.

The second letter defines an oil grade in alphabetic order.

Premium oils on classification API are SG for carburettor engines and CD for diesel engines.

Petrol engines

And – all-weather oils with the raised antifrictional properties, specification VW 500 00.

In – all-weather oils, specification VW 501 01;
    – All-weather oils, specifications API-SF or SG.

Diesel engines

And – all-weather oils with the raised antifrictional properties, specification VW 500 00 (for diesel engines with a turbo-supercharging only in a mix with specification VW 505 00).

In – all-weather oils, specification VW 505 00 (it is unlimited for all diesel engines);
   – All-weather oils, API-CD specification (for diesel engines with a turbo-supercharging only in a special emergency for доливки);
   – All-weather oils, specification VW 501 01 (for diesel engines with a turbo-supercharging only in a mix with specification VW 505 00).