No way to tell without seeing it but if the oil light came back on right after adding two quarts, there is obviously a major leak that just developed. Either that or damage was already done to the engine bearings leading to low oil pressure. Testing the actual oil pressure with a mechanical gauge will show exactly how much pressure is being produced.
On some cars the electric fuel pump is turned on by a switch that turns on from oil pressure. That's a safety feature that turns the pump off in the event of a crash but it also saves the engine when oil pressure gets too low. Your mechanic would know if that pertains to your model. If it does, he will have to bypass that switch to start the engine.
If the oil pressure really is low it's usually due to worn engine bearings. They can usually be replaced without having to replace the entire engine but it's important to inspect the crankshaft. Usually the crankshaft is damaged too and must be replaced. That involves removing the engine.
Sunday, April 15th, 2012 AT 8:19 PM