engines may need flushing

The warning light refers to oil pressure, not level. When it's flashing on and off randomly, or flickering, it is most often caused by a defective sending unit but to be sure the actual pressure should be checked with a mechanical pressure gauge. If the light turns on mostly at low engine speeds and after it's warmed up, it is likely caused by worn engine bearings or in some cases the oil has been diluted with a lot of raw gas.