Describing the three ways in which water may reach the oil-pan, the author says that the danger-point for water accumulation is reached when an emulsion becomes too highly viscous or when an accumulation of free water reaches the pump intake. The effect of using an emulsifying oil is explained and consideration is given the quantities of water actually deposited because of cylinder-wall condensation. An emulsion of oil with water up to 5 or 6 per cent differs hardly at all from the pure oil so far as film-forming and lubricating qualities are concerned. On the other hand, with an oil that is absolutely non-emulsifying, the tendency is for the water to segregate and collect in comparatively large globules. The ability of an oil to absorb a small percentage of water has the advantages of minimizing the danger of complete failure of oil circulation when starting in cold weather and of reducing somewhat the rate of piston-ring and cylinder-wall wear.
Experimental work that enables the rate of deposition of water to be determined was done by the company the author represents, a special engine being constructed for this purpose. Illustrations of the engine and the testing apparatus are presented and a description is included. The work has been continued for many months. Numerous check-runs have indicated that the rate at which water appears in the cylinder oil is shown by a straight-line graph between 35 and 110 deg. fahr., the deposition ceasing at the latter temperature. When continued below 35 deg. fahr, in the same straight line, the graph shows that at 0 deg. fahr, the rate of deposition would be 80 cc. per hr.