Talking about Jseabert'* 93SSE here:

L27, ran very low on oil without his knowledge in a short period of time. No stains on the driveway or in the work parking lot (other than normal mild stains). Ran very low to less than an inch in the pan. Spun some rod bearings (damage to the crank at #4). Most of the crank looks good to mildly scored, cam and lifters look great. Oil pump pickup strainer was not clogged. Cylinder walls are not scored. (inspected all 6).

No evidence of oil leaking from the heads or LIM. New torque converter has no oil on it which COULD possibly rule out a rear main seal leak, at least in that direction.

My thoughts is for the pan to be that empty, it has to be a pressure leak somwhere, not static, but I'll be damned if I can find evidence anywhere on his motor.

Anyone have any theories or guesses?

I agree; I think it would have to be a stream at pressure that leaves little or no drip. The most likely exterior spot for this is around the oil filter. Maybe the oil sender leaks when hot and under pressure spraying a stream to the ground when moving under higher rpm only. This would not occur at idle or when starting up. We had a similar thread a while ago where the a lot of oil was lost quickly with no easy trail. The apparent cause was the oil filter.

EDIT: But if this were the case you would expect to see at least some evidence around the sender or the filter. Are these bone dry?

Not bone dry, some oil residue on both, but not a heavy coating on the sender threads that I could see. On the BODY of the sender, yes, but stuff blows. I'd buy a possible leak at the filter. May have to go over and take another look. It'* still installed on the car.

Has the engine been compression tested before you disassebled it? Is this the reman engine or the really old one that blew?

180k. I know where you're going, and he has no smoke or smell in the exhaust. New trans, old motor.

Bill I saw something very similar in a buddy'* engine.

Here'* the scenario. Engine runs out of oil and smokes bearings. No leaks no indications of where it went. Had recent work done on the motor. Pull dipstick right after turning off and no oil. Wait 5 minutes...you got oil.

I believe when they worked on it some oil return hole got plugged, the oil sat there and cooked the motor since no oil was in the pan.

But if he'* just got disappearing oil period. It'* either in exhaust pipe (would show on plugs), in the tranny...on the ground, or in the coolant. Don't forget... oil pressure is higher than coolant pressure in some areas where the jackets are close to each other.

Say Wil, -I assume this motor is going to be totoally disassembled?

If so, I am really curious about the oil control rings. I had an engine one time that I unknowingly had "stuck" the oil rings, due to excessively high combustion chamber temperatures, which caused the upper half of the pistons (just down past the oil rings) to run too hot. -What happened was I was messing around with air/fuel ratios, and had run the car in an over-lean condition at highway speeds for probably a day. From that moment on, the sucker used oil at the rate of one quart every 200 miles.

Now here is the interesting part of that story: That engine performed perfectly, compression tested perfect, no leaks, no smoke, no smell. It was burning the oil so cleanly that it was not visible. And I think part of the reason for no smoke, was this: the only time that the "oil control" was totally lost, was with the engine running at highway speeds. Under town-driving conditions, lower speeds, lower temps, etc, the cylinder walls were not being "oil flooded." -but were under highway conditions.

-and by the way, the rest of that engine was in perfect condition. -no damage, wear, etc. -just oil rings stuck in their grooves, which made it impossible for them to scrape the oil off the cylinders.

I am WAY CURIOUS to know what you find on this one

mine went on the 94 at around 180k and i replaced it and traded it at 190k for the grand prix. My oil pressure just dropped from 80 to 0 within 5 seconds and seized but there were no leaks at all also. to this day we cant figure out where the oil went to.

I say its oil filter related, somehow?
There would have been signs otherwise, like high oil presure, smells, smoke, etc?