OIL MYTH EXPLODED

Chronicle (Levin), 4 March 1947, Page 4

OIL MYTH EXPLODED

THE TRUTH ABOUT S.A.E. NUMBERS Commenting recently qn the buy-' ing of lubricating oil by S.A.E. numbers, Mr. T. H. Jnnes, Autqmocive Engineer of the Vacuum Oil Company Pty., Ltd. stated that for some time there had been a markcd tendency on the part of mqtpr-r ists to regard S.A.E. numbers as oeing mdicative pf lubricating quality. "Such a trend," said Mr. Innes, "should be cprrected as it places an interpretatiop. on S.A.E. ratings which is entirely foreign to tfle reason for their introduction." Mr. Innes pointed out that the S.A.E. rating of motor oils was orought into general use in 1926 by the Society of Automotive Engineers to provide a standard farm of reference for oil body or fluidity. However, when announcing its numbering system the Society of Automotive Engineers stressed that S.A.E. numbers could not be ,used in any way to indicate the quality of a lubricant.

As the S.A.E. number assesses body at one temperature only, it gives no mdication of an oil's behaviour above or below that temperature., All oils thin out when neated, some more than others. The most desirable oil is that which thins out least when subjected to high engine temperatures and yet remains fluid when cold. An qil qf these characteristics will ensure ready distribution and maximum protection when starting up the engine, and will retain its body when hot to give equal protection at full load. An appreciation of this "doublerange" quality as an essential requirement in a good engine oil, explodes the myth which has become associated in the minds of some motorists that S.A.E. numbers may be taken as a safe guide to lubricating quality. "From the motorist's viewpoint," copcluded Mr. Innes, "the best advice is first to choose an oil of known brand made by a refiner of outstanding reputation, and second, select from that manufacturer's range of oils the grade for your car as • recommended in oil charts at garages and service stations."