FACTORS AFFECTING THE RATE OF CRANKCASE-OIL DILUTION1

This paper deals with progress in the Cooperative Fuel Research since the last report was presented to this Society. Previous tests had shown that the temperature of the jacket water exerted a major influence on the rate of dilution of crankcase oil. The reason for this influence was investigated and it was concluded that it was due to differences in the rate at which diluent was added to or eliminated from the oil-film upon the cylinder-walls, the temperature of this film being dependent upon the temperature of the jacket water. Experiments failed to show that changes in the temperature of the piston head or changes in the viscosity of the oil upon the cylinder-walls exerted a major influence upon the rate of dilution. These conditions were investigated as being probable consequences of a change in the temperature of the jacket water.

Evidence is presented which demonstrates that under certain conditions the diluent may be eliminated from the oil at a fairly rapid rate. The bearing that this has upon the possibility of an equilibrium state being reached is discussed. Considerable miscellaneous information is presented that relates to the manner in which dilution takes place and the influence of various conditions upon its rate.