There are oil additives you can buy in service stations and auto accessory stores and add to the oil yourself.
Most claims for these additives, which usually are thin, oily liquids, are based on their alleged ability to improve engine performance, increase power and economy or cut down engine wear.
Now and then it is possible, one oil expert declares, that such a supplementary additive might have a beneficial effect on a given car. Most oil and auto men seem to agree, however, that these compounds are not necessary for the proper lubrication of your engine. A report by one oil engineer disclosed that 300 such preprations did not contain any material unknown to the petroleum industry itself. Oil companies generally report that their products already contain all the additives that research shows they need, and the companies refuse to stand behind their oils when other additives are used.
Many engineers say that though most of these "special" additives probably do no harm, they do no good, either, and some may actually contribute to deposit and sludge formation or other undesirable conditions.