If a lubrication system fails it’s serious, so it’s crucial to know it’s working. If oil pressure falls too low, a pressure sensor in a gallery can light up a warning light, or register on a gauge.
Low oil pressure can mean a lack of oil. It may have leaked away, or it may have been burned.
This can be caused by worn piston rings which let oil into the combustion chamber.
Some engines even use an automatic cut-out that turns off the engine if oil pressure falls too low.
Too little oil in the engine is a problem but so is too much. The crankshaft can whip it into foam, and cause leaks by flooding the seals..
Of course, the simplest indicator of oil level is still the dip stick.
