95 Pontiac Transport, engine knock - Oil pump or engine shot

1995 Pontiac Transport 3.8L, 195k mi., Oil pressure gauge reads normal when cold, goes down to almost zero as it warms up. Engine runs smooth when cold, but knocks like hell when it heats up, especially under torque. Leaks oil dripping fairly fast when cold (but not once it warms up) around the crankshaft. so.... mechanic thinks the engine is shot, thinks oil is leaking internally, engine bearings etc, and thats why the oil pressure is low. Could it be the oil pump? rebuild is about $250, pump is internal (in engine, not in the oil pan). How can you test whether its the oil pump, or if the engine is shot? i hate to put another $2-300 if its not the problem, and mechanic is skeptical. Any advice?

Also, would a thicker oil buy me some time? What viscosity?? Thanks! 195K, sounds like the rod bearings are shot. If it was the oil pump you wouldn't see any pressure when it was cold either.

He could use plastigauge to measure wear and slap oversize bearings in it. That's if he can get the oil pan off without pulling the engine. Major job on that vehicle to pull the engine. Might buy you a year or two.

Overall, the engine is ready for the big graveyard in the sky. A complete rebuild would cost $1500+. About the engine knock... wouldn't the engine knock badly if it wasn't getting oil? Thats why I am skeptical (or in denial...) that the engine may still have some life left. Last time the oil got too low, it knocked very similar to this, and went away immediately when I refilled the oil. How can you tell between a "no oil knock" and a "my engine is dying knock"?

Lastly, any suggestions on different oil viscosity for the next couple days until I can get it fixed?

Much thanks!!!!! You said oil pressure was normal when it was cold then dropped to nothing when it was warm. This is typical of worn rod bearings. Because the oil viscosity is thicker when cold and the metal is cold, pressure will build. As the motor and oil warms up, the oil starts oozing out the sides of the worn rod bearings instead of continuing up the oil passages and oil pressure drops.

If you are losing oil.... leaking or worn rings?? The engine is going to knock too if you run the pan dry.

Either knock is a dying knock as the bearings lost their lubricating factors. One way is already worn bearings and the other is creating worn bearings. Your last question. The thicker the oil, the better...20W50.Car Repair Talk's forum.