Why does oil warning light come on when oil level is ok?

Answer 1

The oil warning light has little to do with oil level other than the fact that without oil the engine cannot generate oil pressure. Babbit bearings, the type of bearing used in all internal combustion engines consist of a finely machined, perfectly cylindrical surface on a crankshaft or camshaft and a finely cast babbit bearing insert that fits into the engine block. During engine operation the oil pump creates pressure that is injected into rod, main and crankshaft bearings through oil "journals" that are through the block, allowing the pressurized oil to reach critical bearing surfaces. The babbit bearings have holes that align with the holes in the engine block. During normal engine operation, pressurized oil reaches the babbit bearings, supporting the crankshaft/camshaft and keeping the moving parts from actually touching. When oil pressure drops it is because the babbit surface has been partially worn away and oil leaks out past the bearing surfaces at a rate that is too high for the oil pump to maintain the pressure required for the engine to function as designed. Lower oil pressure is usually an indication of worn main or rod bearings. The solution is expensive. Thicker oil or an oil thickener can help reduce the rate at which the oil leaks past the bearing surfaces but these are only methods to squeeze a little more life out of an ailing engine. Select an oil with a higher viscocity number and you MAY be able to slightly raise the oil pressure.