1995 Toyota Corolla - Where's my oil going?

1995 Toyota Corolla, 4 cyl, 1.8L engine with 240,000 miles, driven 15,000 miles per year. Automatic transmission.

I have regularly changed oil every 5000 miles.
Within the last two oil changes, I have noticed oil loss when checking the dipstick at a rate of about 1 qt / 2500 mi, and I have been topping off between oil changes.

There is no visible oil leak. No oil dripping on the ground. No white smoke coming out of the tail pipe. No oil in the radiator. Engine compression is still good, as there is no loss of acceleration or fuel mileage (30 mpg).

Last repairs we replacing the EGR solenoid valve after getting a check engine light and replacing the PCV valve, but neither helped with the oil loss.

Where else could the oil be going? What am I missing?

If it’s not leaking oil then it’s burning it past the piston rings and valve seals. That’s to be expected at almost a quarter million miles and a quart per 2500 miles is not bad at all for the age and mileage.

It would be near impossible to visibly determine oil burning by watching for smoke due to the low amount of oil being burned and the fact that the catatlytic converter is catching what smoke there is.

You cannot determine if compression is good based on acceleration and fuel mileage.
A compression test or a leakdown test needs to be performed. Even those tests are not 100% definitive but it’s the best there is. There is no test for valve seals.

"Where else could the oil be going? What am I missing? "

Nothing lasts forever, the engine is getting a little tired…A quart every 2500 miles is nothing…

Some brand new engines burn a quart per 2500 miles, and it’s considered normal.

Thanks for the responses. Not planning to keep the car forever, but I was concerned when it suddenly started going through much more oil than it had been for many years. I’m totally grateful for all the use I got out of this car, and any additional miles I get is gravy.

Your increased oil consumption isn’t necessarily due to mechanical wear, which timely oil changes can prevent.
It could be that the piston rings are losing their spring tension, and don’t wipe the oil off of the cylinder walls as well as they used to.

While you’re probably just losing more oil past the rings as has already been suggested, do note that the PCV valve itself is only one part of the PCV system. You might want to just check its inflow & oulflow paths.

Lobbybee, I had the EXACT same car that you do… great little car.

I had the EXACT same issue… she needed about a half-quart every 1000ish miles between changes, and there were absolutely NO visible leaks anywhere to be found on the car. After doing all the compression tests, I finally stuck my friend’s camera scope down into the cylinder. The hash-marks of a fresh cylinder hone were polished away to an almost mirror-like finish, and a mildly oily residue was visible along the edge of the piston just above where the top ring would be… still had good compression though. This led me to believe that the cylinders were worn into an elliptical shape just enough to let oil by.

I too had a high mileage engine, and it ran exceptionally well all the way to 290 when the oil pump went while I was on the highway, and the rapid loss of pressure at high RPM threw a rod and my machine was left sounding like a diesel Hilux pickup. I even drove it about 1/4 mile to the exit ramp with no oil pressure just to get it off the highway with a small shoulder and tractors driving by at 70mph.

Keep two quarts in the trunk, and drive it to 300K (or more). If you’re a cheap bastard like me, wait until it grenades on you and swap in a junkyard motor, and drive it another 100K and sell it for a decent coin in this economy where everyone wants 4 cylinders with gas nearing $4. I would have sold mine if an old lady hadn’t side-swiped it while it was parked in a metered spot.

Oh yeah, the fact that it’s a '95 is desirable in nanny-states like my native NY with emissions inspections. Pre-96 vehicles were not mandated by law to have the OBD-2 communications standard, so it’s one less thing to worry about every year, so anything older just has to go through a safety inspection to make sure it’s not a complete death-trap.