Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 6 reviews
Yes, when the oil pressure light comes on, it's probably too late. The pressure sensor that turns the light on is set to do so at around 2 psi. The oil pump can maintain pressure above this level even while at the same time insufficient oil is actually moving to the critical areas. It's much the same on all cars. The oil pressure light is just that -- it indicates that the pump is working. But, unfortunately, it does not indicate if enough oil is actually moving to lubricate the engine.
If the oil pressure light comes on (presumably due to loss of oil), it means that the pump can't draw up enough oil from the sump to develop pressure on it's output side.
When the engine oil level gets low, one sign is often noticeably more tapping noise, clatter, etc from the engine.