low pressure top end

My engine oil light came on. I got the car towed to a mechanic. He checked and told us that there is a valve that prevents all the oil from runnng to the bottom of the engine when the engine is shut off. It is stuck and now there is no or low pressure in the top end. The car isn't worth the $1400 he wants to charge to probably rebuild it. There isn't any engine knock YET. I am wondering if there is a way or something to add to the oil to possibly get this unstuck. Otherwise another Malibu engine (the second for this car) bites the big one. Any help would be appreciated. Thanks.

Welcome to AF, not knowing what engine you are referring to, never heard of this diagnosis before, what valve, pressure relief in the oil pump?

Sorry. It is a Chev Malibu, 2.2L. I was told there is a valve that prevents the oil from running back to the bottom of the engine when it is shut off. Prevents a dry start. I would assume that this is somewhere in the top end. Never heard of this one before but I trust the mechanic.

There is a drain back valve in the oil filter, if there is such a device in the 2.2 it's new to me. The oil is supposed to drain back to the oil pan on shutoff, get more details on what and where this is.

I have never heard of this valve either. Many oil filters have a very simple anti-drainback valve in them. But that valve is changed whenever you change an oil filter.

I would be suspicious of this mechanic. There are many reasons why an oil pressure light would come on.... bad wiring, bad oil pressure sensor, broken oil pump or pump drive, clogged oil pick-up screen or filter, low oil level, etc. Imo all these need to be checked out, before some 'valve' (which may not exist) is blamed.

The first thing to do is to install a separate oil pressure gauge to the engine, in place of the original sensor, then start the engine. This will immediately tell you if the engine is at fault, or the sensor. If it is the engine, the next thing to do is to remove the oil pan and inspect the pump and pump drive.