OIL AND OIL PRESSURES.

King Country Chronicle, Volume XXVI, Issue 3440, 8 March 1932, Page 2

OIL AND OIL PRESSURES.

The oil pressure gauge shows only the pressure at which the oil is being circulated through the pressure system.

However, the question is: Should the oil pressure be high or low? In recent years oil pressures have increased hand in hand with faster engine speeds and higher compression ratios. But, surely, a high oil pressure does not mean that a greater

quantity of lubricating oil is being forced through the bearings than when a low pressure is employed. For instance, if there were a blocked oil pipe, would not the pressure as shown by the gauge be higher? But obviously there would be less oil reaching the bearings.

This example only goes to show that a high .oil pressure does not necessarily mean a copious flow of oil through the bearings. No matter whether a high or low pressure oiling system is employed, a more or less sudden rise in pressure indicates a blockage in the system, and that the bearings are probably being starved.

The oil pump itself must be designed to deliver an adequate flow to the various main, big-end, and other bearings so that there will be no fear of oil shortage in the motor at all. If the bearings are tight-fitting and the oil pipes of large cross section the pressure as shown by the gauge on the dash will be low, but because the oil-ways are not so restricted there will be a greater flow through the bearings and better lubrication of the motor. A low pressure system, therefore, does not necessarily mean that the pump itself is delivering a small flow of oil. Of course, the pressure in any system will vary with the oil used. Should an oil that is "gummy" or sluggish at low temperatures be used in the motor, the oil pressure gauge will, immediately upon starting the engine, show a very high pressure, and this will probably decrease as the oil becomes warm and freer flowing, and, in this case, as the pressure decreases the flow through the bearings becomes greater.

But if the oil is diluted or thins out excessively at high temperatures (a sign of an inferior oil), the pressure gauge will show a further drop in pressure as soon as the motor becomes really hot. However, for a second or two after starting the oil pressure gauge in all cars shows a higher reading than normal. The best oil to use is the one which is freer flowing at low temperatures and maintains its body at the highest operating temperatures. This essential quality of the oil will be shown by the pressure gauge in that the pressure will vary only a little between the highest and lowest operating temperatures.