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This paper describes engine rusting obtained in three closely controlled, “Aunt Minie” passenger-car, field services tests. Under severe conditions imposed both by the mode of operation and winter weather, appreciable engine rusting was observed. In addition to the major effect of lubricating oil on rusting, other important influences were fuel scavenger and operational variables such as ambient temperature, engine temperature, and crankcase ventilation. The range of motor oil antirust performance found in severe field service appears to be inadequately predicted by existing laboratory engine rust tests. Better definition by laboratory tests is desirable to permit selection of motor oils of adequate antirust performance.

This paper discusses trends in engine lubricant developments in terms of lubricant functions and in relation to such factors as advances in refining technology and changes in engine designs. Recent development trends in engine lubricants for passenger cars, heavy duty trucks, and diesel powered equipment, piston engine aircraft, LPG and natural gas engines, and outboard engines are summarized, with emphasis on passenger car lubricants.

Wear and corrosion in gasoline engines are strongly influenced by the halogen acids formed during the combustion of fuels containing tetraethyllead and the accompanying chlorine and bromine scavengers. While modern technology in metals and lubricants has provided improved products which tend to resist and supress wear and corrosion, this paper presents another approach, namely, the reduction of halide scavengers which are major contributors to the problem. The results of numerous tests both in the laboratory and on the road show that reduction of fuel halide scavenger concentration does significantly diminish corrosive wear and rusting in gasoline engines. Furthermore, these benefits are realized in passenger car service with no adverse change in engine performance or durability, as long as the fuel contains a phosphous combustion-chamber deposit modifier.

AN experimental program to determine the influence of crankcase oils on scuffing and pitting of cams and tappets in overhead-valve V-8 engines is described in this paper, which is part of a Symposium on Cam and Tappet Wear. Results indicate that certain additives may eliminate, while others actually promote, scuffing and pitting of a particular type of surface. At the same time, the protection afforded a tappet surface by any particular additive depends upon the tappet material. An additive that protects steel lifters from scuffing may cause chilled iron tappets to pit. In the authors' tests hardenable cast iron was found to be the easiest tappet metal to lubricate. Discussion of this and the other papers in the Symposium starts on p. 220.