OIL MYTH EXPLODED

Wanganui Chronicle, 26 February 1947, Page 6

OIL MYTH EXPLODED

THE TRUTH ABOUT S.A.E. NUMBERS Commenting recently on the buying of lubricating oil by S.A.E. numbers. Mr. T. 11. Inn.-., Automotive Engineer of the Vacuum Oil Company Pty., Ltd., stated that for some time there had been a marked tendency on the part of piotorists to regard S.A.E. numbers r.s being indicative of lubricating quality. “Such a trend, said Mr. Innes, “should be corrected as it places an interpretation on S.A E. ratings which is entirely foreign to the reason for their introduction.” Mr. Innes pointed out that the S A.E. rating of motor oils was brought into .general use in 1926 by the Society of Automotive Engineers to provide a standard form 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 indication of an oil’s behaviour above or below that temperature. All oils thin out when heated, 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 oil of these characteristics will ensure readv 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,” concluded 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.”—P.B.A-