BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

Which of car owners, even seldom looking under a cowl, did not pour at least once this amber liquid in the engine of the favourite? Who at least once did not examine multi-colored canisters on shelves of autoshops? What oil to choose what is meant by all these inscriptions and brands? As conveniently and just there was earlier, here a Zhigulyovsk oil, and here for all the rest. And now...

Why it is impossible to make, say, oil one for all cars that the motorist did not suffer?

Alas, so it is impossible, at least, today though properties of engine oils so improved lately that it is almost impossible to make a gross blunder at the choice. And nevertheless operating conditions of oil during a heat and cold, in the petrol engine and the diesel moreover and with pressurization too differ. And everywhere from oil it is required to divide reliably rubbing surfaces, without allowing metal contact, to wash away the smallest particles of wear and a nagaroobrazovaniye, to interfere with corrosion, to take away heat, to wash away lakoobrazny deposits, not to be oxidized, not to foam, to get denser not too on a frost and to be diluted not too at high temperature, not to form rainfall and, at last, not strongly to change all these qualities eventually. For this purpose the whole complex of additives is entered into oil: washing, antifoam, depressatorny (that did not get denser in a frost), antiwear, etc. Some additives combine in themselves several functions, for example, barium dialkyldithiophosphate - it is at the same time antiwear, anticorrosive and washing additive.

In the USSR worked and GOST 17479.1-85 defining properties and marking of oils for piston automobile engines continues to work now. Depending on operational qualities six groups of oils on extent of speeding up and type of engines for which these oils are intended are established.

Group A – for not forced, the B – low-forced, In – sredneforsirovanny and – the high-forced engines. Besides, there is still a group D – only for the high-forced diesels and E – too for diesels, but stationary and ship, using fuel with high content of sulfur. Besides, oils of groups B, B and G are in addition subdivided on carburetor with an index 1 and diesel (index 2). Lack of an index says that oil is good both in the diesel, and in the petrol motor, but certainly, this group on extent of speeding up.

Other indicator which is been the basis for domestic classification is viscosity of oil in santistoks (cSt) at the working temperature taken for 100 °C.

In order that oil easily allowed to start the engine on a frost and at the same time kept the viscosity during the work, enter zagushchayushchy additives into it – polyisobutylene. It is the long molecular chains having property at a low temperature to gather in balls. In such state they almost do not influence viscosity of oil, it remains rather liquid. At temperature increase balls of molecules "are unwound" and zagushchat oil, increasing its viscosity. So receive the all-weather brands of oils having the index "z" in designation.

So, here example of interpretation of domestic designation: M12G – the engine oil having viscosity about 12 cSt at 100 °C of group G that is for the high-forced petrol and diesel engines. Summer it or winter? And in general, what is winter and summer at a conversation on oils? It is considered to be that the winter is when average air temperature is generally below 5 °C, and the summer – is above 20 °C. Besides, if the car is operated under trying conditions (the mountain area, sandy and dirt roads), it is necessary to apply oil of the increased viscosity. M12G is a summer grade. It is more preferable to use M8G oil in the winter. Though it is necessary to tell that most of motorists prefers to these brands all-weather M53/10G1 or M63/10G1 oils for a long time. Such marking means that this oil at 100 °C has viscosity of 10 cSt, and on a frost behaves as 5 or 6 cSt, winter with viscosity. The letter "z" – means thickened, but not winter as many consider. M53/10G1 oil more liquid, it suits for use in a midland and northern areas during the whole year. M63/12G1 oil is suitable for warm edges more as more viscous.

Our classification at all its informational content is quite bulky, difficult to pronounce, and, above all, – it is not absolutely clear what is the small, average and high-forced engine.

Around the world today two types of designation of engine oils are accepted: on operational properties (API) and on viscosity (SAE).

The first type of classification is offered by the American oil institute and looks as a combination of two letters: S (service) for petrol engines or the C (commercial) for diesels with the additional letter showing degree of perfection of oil. And this degree is expressed quite originally – in years of production of engines for which this oil is intended. So, SA is an oil without additives for the oldest motors; SB – is newer to engines; SC – for cars of 1964-67 of release; SD – for motors of 1968-72; SE – for the cars released since 1972; SF – since 1980. Certainly, it is about foreign cars, modern Russian cars correspond to the classes SE, SF. Two last classes – SG and SH – are intended for the newest cars. As you can see, letters in the Latin alphabet still remain much so at improvement properties of oils of problems with marking will not be.

Reference

Society of automobile engineers (SAE) offered classification by viscosity at 100 °C. It looks so: SAE 20, SAE 40, etc. If oil winter, then is included into its designation the letter "W". All-weather oils are designated by the same principle, as domestic, only through a dash, for example: SAE 20W-50. It is only necessary to remember that these figures – not santistoksa. For example, M63/14G1 oil corresponds to SAE 15W-40. Marking of all foreign oils contains, except the name of firm manufacturer, both types of designation, for example: Mobil SAE 10W-50 API SF. Sometimes in marking the words Super, Extra, Diesel, Turbo, Multigrade (all-weather), etc. meet.

The mineral, that is received from oil, engine oil has as it was already noted, the following shortcoming – strong dependence of viscosity on temperature. To reduce this phenomenon, enter zagushchayushchy additives. But here a trouble, they quickly enough collapse because of high mechanical and thermal loadings. Especially it is noticeable on worn-out engines where after the run in several hundreds of kilometers on new all-weather oil suddenly the emergency red bulb lights up again. What to do? To pass to more dense summer? But winter outside, you will not start the motor in the morning. An exit – in use of synthetic oil.

They are received by chemical synthesis, than high uniformity and stability of properties is reached. But the most important – viscosity of "synthetics" changes from temperature a little, that is it more liquid on a frost and more dense during a heat, than "mineral water". Wear of details and loss on friction will allow to reduce this property that saves fuel – about 2-3%. Besides, "synthetics" burns down in the engine less and in general serves longer, forming few deposits. It is easy to distinguish synthetic oil on the inscription "synthetic", and also on wide temperature range: 5W-40, 10W-60, etc. The only thing that is bad – high price, approximately in 2,5–5 times more, than at mineral oil. Therefore there is a compromise – semi-synthetic oils, that is mix of "synthetics" with mineral (it is not obligatory for 50/50). It is necessary to consider that additives you should not do such mix, mineral oil can not be dissolved in synthetic. "Blood clots" in oil channels are as a result formed.

Reference

As for mixing of two mineral or two synthetic oils, it – please. Also do not trust various instructions where it is forbidden to mix oils of different firms. Modern oil surely passes an omologation, that is the admission to application, and one of points of this procedure is the certificate of full compatibility. And really, you can imagine the American car owner who would have to remember constantly what oil is filled in in its car? When mixing various domestic oils it is possible to use a formula:

X = Ay + B (1 – y),

where X – viscosity of mix, A and B – viscosity of the mixed oils, y – a share of the first oil in mix.

Several words about the choice of oil depending on a condition of the engine. In the period of a running in intensively brings wear products out of couples of friction and therefore it should not be dense. Best of all here SAE 20, SAE 30, and from all-weather SAE 20W-30, 10W-30, 5W-30 will approach. In the period of "maturity" SAE 30, 20W-30, 15W-30, 10W-40 suit for VAZ motors. It is better not to use more dense because of danger of oil starvation in cold season yet. And here BONDS engines and MEMZ-968 need something more dense as the first has more gaps and oil scraper rings, and at "Zaporozhets" high thermal stress is worse. Apply SAE 20W-40, 10W-50, 10W-60 here. The same oils suit also for any "elderly" motors.

Whether it is necessary to wash out the engine when changing oil? If the car used high-quality oil all the time, then – no, but, at least, time in two years or each 30000 km it is worth washing out the motor nevertheless. Especially, now on sale there are structures turning the filled-in old oil into flushing. It is not necessary as earlier, several times to pour out and fill in, and all procedure of washing will take away from you 5–15 minutes.