Oil Consumption as Affected by Engine Characteristics 310009
THE PROBLEM of oil consumption must be solved before the problem of winter starting and winter lubrication can be solved, asserts the author, since winter starting and winter lubrication require light oils, and light oils give poor results as regards oil consumption.
Eight factors affecting oil consumption are listed in the order of their importance. Some of the reasons why they affect oil consumption are given and suggestions as to methods of overcoming the difficulties are made.
The author concludes that oils of low viscosity, which are required for winter starting, can be made to give satisfactory oil consumption at all engine speeds by necessary changes which probably will involve other mechanical features besides those usually considered in connection with design of the lubrication system. They may include improved bearings, oil-coolers, air-cleaners, oil-filters, better control of cylinder and piston cooling, and other factors. Certain changes in some of the lubricants themselves may be necessary. Much progress has been made in this work by both the oil industry and the automobile industry, and only by continued work and cooperation can success be attained.
One discusser* of the paper believes that engine speed and oil leaks are the only factors of real importance affecting oil consumption, and points out that complete oil changes at 1000-mile intervals greatly reduce the miles obtained per quart. Cooperation of the oil companies is desired in making generally available in summer an oil that is suitable for use in the running-in period of new cars. Oil-coolers and improvements in bearing metals to increase their heat conductivity and heat resistance to enable them to sustain higher loads are expected to increase the safe temperature at which engines can be operated.
Results of tests made on the Indianapolis Speed-way to ascertain the effect of speed and viscosity on oil consumption and of engine temperature on carbon deposition are given by another discusser.
Data obtained in tests of a passenger-car engine and a truck engine showed that engine variables, such as speed, timing of valves and ignition, and condition of the piston-rings, affect oil consumption much more than do the properties of the oil.
Extensive data obtained in cold-starting and oil-consumption tests are presented in a written contribution and appear to show the superiority of dewaxed zero-pour-test oils in resistance to viscosity change with temperature change, making one grade of oil instead of three suitable for both summer and winter operation.