OIL CONSUMPTION

Rotorua Morning Post, Volume 1, Issue 94, 11 December 1931, Page 2

OIL CONSUMPTION

THE FACTOR OF SPEED When the driver raises the speed of his car from 30 miles an hour up to 55 he inereases the lubricating oil consumption of the engine six or seven times. That is one of the interesting facts developed out of a 9,000 miles test recently conducted at the Indianapolis speedway by the contest board of the American Automobile Association acting for the Standard Oil Company of Indiana. Thirteen new stock cars, representing a cross-section of the 1981 production models were used in the test. After a 2,000 miles run-in two tests were made at 30 miles an hour and flve at 55 miles an hour. The complete test is said to be the most extensive and important the Ameri-. can Automobile Association has ever made. It permitted the accumulation of more than 600,000 separate obseryations, which have provided the basis for determining numerous new facts regarding motor-.car operation. It was found that the cars used an average of one quart of oil per thousand miles at 30 miles an hour, but jumped up to 6.9 quarts per thousand | miles at 55 miles an hour. Engineers regard this finding as proof that the modern tendency toward driving at high speed is the main factor causing variations in oil consumption. On the question of the advantage of using heavier grades of oil to reduce consumption, a direct comparison between medium, heavy, and • special heavy grades, all other conditions being equal, showed that consumption at high speed can be re- » duced about one-third by using the i heavy summer oil in place of light 1 winter oil. But this saving is at the expense of loss in the petrol mileage, as 7 per cent. greater petrol mileage was obtained when using the lighter oil, probably as the result of lower internal friction in the engine. The reason appears to be that there is no good reason to vary from recommended viscosities, §ven for high speed driving. As has been expected, the test showed that the amount of carbon deposited was smaller at the high speeds, with the engines running eomparatively hot, than at 30 miles an hour. The association verified by its findings the claim that prediluted oils do not thin out in the crankcase. The prediluted oils were slightly thicker at the conclusion of each test than at the beginning, owing evidently to evaporation or consumption of lighter parts of these oils. Findings of the board also verified the claim that ethylised gasoline prevents detonation in the engine. None of the engines at any time showed any evidence of a knock. As the result of lubrication in accordance with standard recommendations, contest officials reported that all mechanical parts outside the motors had funetioned perfectly and without distinguishable wear.- On pistons and cylinders the wear was too small to be measured at thousand mile intervals, and was less than onethousandth of an inch for the entire nine thousand miles.