The first thing to do is measure the actual oil pressure with a mechanical gauge. Auto parts stores that rent or borrow tools will have one. If the pressure is okay, the new sending unit could be defective, but more commonly a wire might be rubbed through and grounding out against the engine. The clue is the oil light will stay on when the plug is removed from the sending unit.
If the pressure really is low, the two common causes are worn engine bearings and debris in the oil pan that is blocking the oil pickup screen. If the bearings are worn, the pressure will be higher if you switch to a thicker oil. The pressure will drop as the oil gets warmer too. This problem comes on gradually. At first the oil light will come on at idle and go off at higher engine speeds.
If there's debris in the oil pan, often the pressure will start out fine, then drop suddenly. The pressure may drop when you increase engine speed.
Jun 4, 2014 at 11:11 PM
