Simulated start-up tests were made in a cold chamber with two gasoline-fueled four-cylinder passenger car engines. The engine was motored with a hydraulic motor according to a certain test programme.
The time required for the oil pressure to build up was measured on the camshaft bearing which is the most remote point of the lubrication system. The oil pressure in the smaller engine was also measured before and after the oil filter. The torque required for motoring the engine and the temperature of the oil, one main bearing and one camshaft bearing were also measured, in addition to the motoring tests, start-up tests were made with the other engine to get information about the correlation of the motoring test results with a start-up situation in practice.
At ambient temperatures < 20 °C there were differences especially in the pumpability properties of oils even within the same viscosity class. Hence, the choice of oil and the use of auxiliary heaters are of great significance.