BMW 3 series E30

Since 1983-1994 of release

Repair and car operation

14.9. Engine oils

THE GENERAL DATA

Who from the automobile owners even seldom looking under a cowl, did not pour at least time this amber liquid in the engine of the favourite? Who at least time did not examine multi-coloured canisters on regiments of autoshops? What oil to choose, what mean all these inscriptions and marks? As oil "Zhigulevsk", and here for all the rest was convenient and simple earlier, here. 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 have improved lately what to make a gross blunder at a choice it is almost impossible. And nevertheless oil working conditions in a heat and a cold, in the petrol engine and a diesel engine, moreover and with pressurisation too differ. And everywhere from oil it is required to divide reliably rubbing surfaces, without supposing metal contact, to wash away the smallest particles of deterioration and нагарообразования, to interfere with corrosion, to take away heat, to wash off лакообразные adjournment, not to be oxidised, not to foam, not too to get denser on a frost and not too to be diluted at a heat, not to form deposits and, at last, not strongly to change all these qualities eventually. For this purpose the whole complex of additives is entered into oil: washing, antifoamy, депрессаторных (that did not get denser in a frost), противоизносных, etc. Some additives combine in themselves some functions, for example, диалкилдитиофосфат barium is simultaneously противоизносная, an anticorrosive and washing additive.

In the USSR operated and GOST 17479.1-85 defining properties and marks of oils for piston automobile engines continues to operate now. Depending on operational qualities it is established six groups of oils on degree of speeding up and type of engines for which these oils are intended.

Group And – for not forced, – малофорсированных, In – среднефорсированных and Г – высокофорсированных engines. Besides, there is still group D – only for высокофорсированных diesel engines and Е – too for diesel engines, but stationary and ship, working on fuel with the big maintenance of sulphur. Besides, oils of groups, In and Г are in addition subdivided on carburettor with an index 1 and diesel (an index 2). Absence of an index says that oil suits both in a diesel engine, and in the petrol motor, but certainly, the given group on speeding up degree.

Other indicator taken as a principle of domestic classification, viscosity of oil in сантистоксах (сСт) is at the working temperature accepted for 100 ° With.

That oil easily allowed to start the engine on a frost and at the same time kept the viscosity at work, into it enter загущающие additives – полиизобутилены. These are the long molecular chains having property at low temperature to gather in balls. In such condition they do not influence almost viscosity of oil, it remains liquid enough. At rise in temperature balls of molecules "are unwound" and загущают oil, raising its viscosity. So receive the all-weather marks of oils having in a designation an index "з".

So, here an example of decoding of a domestic designation: М12Г – oil motor, having viscosity approximately 12 сСт at 100 ° From group G, that is for высокофорсированных petrol and diesel engines. Summer it or winter? And in general, what such winter and summer at conversation on oils? It is considered to be that the winter is when average temperature of air basically more low 5 ° With, and the summer – above 20 ° if the car is maintained d under trying conditions (mountain district, sandy and dirt roads), it is necessary to apply oil of the raised viscosity. М12Г is a summer grade. It is more preferable to use oil М8Г in the winter. Though it is necessary to tell that the majority of motorists prefers for a long time already to these marks all-weather oils М53/10Г1 or М63/10Г1. Such marks mean that this oil at 100 ° With has viscosity 10сСт, and on a frost behaves as winter with viscosity 5 or 6 сСт. The letter "з" – means загущенное, instead of winter as many consider. Oil М53/10Г1 more liquid, it suits use in a midland and northern areas within all year. Oil М63/12Г1 approaches for warm edges, as more viscous more.

Our classification at all it информативности is bulky enough, difficult to pronounce, and the main thing, – is not absolutely clear that such it is not enough - sredne - and высокофорсированный the engine.

All over the world today two types of a 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 C (commercial) for diesel engines with the additional letter showing degree of perfection of oil. And this degree is expressed in an original way enough – in years of manufacture of engines for which this oil is intended. So, SA is an oil without additives for the oldest motors; SB – for engines поновее; SC – for cars of 1964-67 of release; SD – for motors of 1968-72; SE – for the cars which are let out since 1972; SF – since 1980. Certainly, it is a question of foreign cars, modern Russian cars correspond to classes SE, SF. Last two classes – SG and SH – are intended for the most newest cars. As you can see, letters in the Latin alphabet still remains much so at improvement of properties of oils of problems with marks will not be.

The inquiry

The society of automobile engineers (SAE) has offered classification by viscosity at 100 ° to S.Vygljadit it so: SAE 20, SAE 40, etc. If oil winter its designation includes 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 necessary to remember only that these figures – not сантистоксы. For example, oil М63/14Г1 corresponds SAE 15W-40. Marks of all foreign oils contain, except the firm-manufacturer name, both types of a designation, for example: Mobil SAE 10W-50 API SF. Sometimes in marks there are words Super, Extra, Diesel, Turbo, Multigrade (all-weather), etc.

Mineral, that is received of oil, engine oil has, as it was already marked, the following lack – strong dependence of viscosity on temperature. To reduce this phenomenon, enter загущающие additives. But here a trouble, they quickly enough collapse because of high mechanical and thermal loadings. Especially it is appreciable on the worn out engines where after run in some hundreds kilometres on new all-weather oil suddenly the emergency red bulb again lights up. What to do? To pass to more dense summer? But after all winter on a court yard, in the morning the motor you will not get. An exit – in use of synthetic oil.

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

The inquiry

As to 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 necessarily passes омологацию, 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 automobile owner who should remember constantly, what oil is filled in in its car? At mixing of various domestic oils it is possible to use the formula:

X = Ay + B (1 – y),

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

Some words about a choice of oil depending on an engine condition. During the period обкатки intensively deduces products of wear process from friction pairs and consequently it should not be dense. Is better here will approach SAE 20, SAE 30, and from all-weather SAE 20W-30, 10W-30, 5W-30. In "maturity" for вазовских motors suit SAE 30, 20W-30, 15W-30, 10W-40. More dense are better be not to using yet because of danger of oil starvation in a cold season. And here engines to BONDS and MeMz-968 need something more densely as the first has more backlashes and high thermal stress is worse маслосъемные than a ring, and at "Zaporozhtsa". Apply here SAE 20W-40, 10W-50, 10W-60. The Same oils suit and any "elderly" motors.

Whether it is necessary to wash out the engine at oil change? If the car all time worked on high-quality oil – is not present, but, at least, time in two years or each 30000 km to wash out the motor nevertheless costs. Especially, now on sale there are the structures transforming filled in old oil in промывочное. It is not necessary, as earlier, some times to pour out and fill in, and all procedure of washing will take away from you 5–15 minutes.