You may remember learning about carbon-atoms in your chemistry class. The model has four arms, onto which other atoms can be attached. Officially, it is described as being tetravalent. Thereby, any number of combinations can arise, because these atoms can be connected to atoms of the same type. Thus, chain- and also ring-shaped structures are possible. In the distillation, the resulting engine oil is separated from the remaining mineral oil products. Typical are the large number of different remaining compounds of carbons- and hydrogens (according to weight, almost 90 to a good 10%), from which the final mineral oil product is made up. This is of course, not valid for synthetic oils.
We are assuming a mixture of various hydrocarbons after the vacuum distillation. On top of that, this distillate is not free of other elements, like oxygen and sulphur. The further processing in the refineries, intervenes precisely in the described molecular structure. In addition, unwanted elements are removed, e.g., in the desulphurisation process. The difference in the further processing to synthetic oils, is that, in this case, the chain, as it were, is radically shortened, whereby, base-oils stay the way they are and 'only' through certain chemical processes are freed specifically from unwanted substances.
With synthetic oils it concerns rather the reduction of the core of the hydrocarbons, while the base-oils with their multiple branched hydrocarbons, maintain the given structure. In the end, longer chains also exist here, however, through 'synthesizing'. What is planned is a relatively even, absolutely desired structure made up of single parts. The properties are created, which apart from the, without a doubt, important lubrication qualities, also the others descibed in the course of this article. Depending on the purpose for which it is later to be used, e.g., in motorcycles, conflicts can arise, which appear to make the oil unsuitable for motor car engines.
The reason for this is that as a rule, a motorcycle engine only has one oil circuit for the engine, the clutch and for the gearbox. Now, in the past, engine oil in the gearbox has sometimes even been stipulated by the manufacturer. If one is stuck in the desert, and the only way out is to put engine oil in the gearbox, I wouldn't hesitate for a minute. Indeed, in the meantime, the oils have become so specialized, that real defferences can be observed. Modern manual gearboxes have a hard time with the very thin, synthetic oils, unless they have been specifically designed to use them. If a wet-clutch, like some motorcycles have, is also in existence, then through increased impurities coming into the oil, it becomes more difficult to find a common base.
It is not without reason, that since 1999, the Japanese Automotive Standards Organisation specifacation was created. Here one can see, that the country with the highest motorcycle production was very interested in establishing their own ruling. In the motor car engine, that which is continuously being improved, the low frictional properties, can, in some component groups in the motorcycle engine which rely on friction, lead to problems. The solution is probably, synthetic oils which have been specially designed for use in motorcycles, because on no account do the manufacturers want to do without the advantages of the completely different production of oils.
One sometimes hears the saying, only use as many additives as are absolutely necessary, because this would mean less base-oil and the lubricating qualities would be reduced. There is some truth in this, e.g., as far as the shear-stability is concerned, which in the additives, is not as strongly formed as in the base-oil. 11/11