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Severe oil loss, no visible leaks, no blue smoke

(2004 Volvo V70)
in Burlington, MA on August 14, 2011
105K. Adding a quart of oil every 900 miles, no visible leaks. No smoke coming out of the pulled oil dipstick with the engine running. What could it be? I read on some forums that a clogged or faulty PCV could be causing oil loss, but then there would be smoke coming of the oil dipstick or the add-on oil cap. No blue smoke coming out the tailpipe neither. Mileage is good (30mpg when doing highway only).
How much does diagnosing a problem like this and what does it involve? Measuring cylinder pressure? Taking the engine apart and looking at oil rings, valve seals? I think the problem started after a modest fender bender after which I brought the car to a body shop to replace some stuff on the front (headlight, etc.). They must have had to remove some hoses, etc. and put them back after the body work. Could it be caused by the body shop not tightening some hose clamps or something as simple as that?
Displaying 2 answers & 2 comments
Popular Answer
on August 14, 2011
There does not have to be smoke from the dipstick hole for there to be a PCV problem. If the PCV system is just sucking oil in to the engine, say from a defective PCV system/check valve etc, there would be no smoke from the dipstick. I would first have a good diagnostic shop conclusively find out where the oil is going and why.

here are some shops:
on August 15, 2011
If it's not leaking oil, then it could only be burning oil. If you want to try and fix this yourself, then go to a dealership parts department and purchase a pcv valve and trap if this car has one. If problem persists then the problem is more serious, rings, valve seals, etc. A cylinder leak down test would be good to do.
Is this engine turbo charged?
on August 15, 2011
To answer the previous comment - it's not a turbo - just a plain 2.4 5-cylinder.
I bought a manometer kit to measure the cylinder pressure a while ago but haven't figured out what to disconnect to prevent the engine from starting when having the starter turn the motor while testing... The kit came with simple instructions on how to diagnose problems (like pour a spoon of oil in the cylinder and test again to see if pressure improves. If it does - must be oil ring, etc.). Not sure if doing this kind of testing will give any reliable answer.
I'm thinking of giving it a course of Auto-RX before I invest in a more expensive diagnostic or repair - hope this won't make whatever problem there is worse.
I was advised to remove the oil dipstick and place my thumb on the opening to see if there is any positive or negative (vacuum) gas pressure with running engine. On idle, there seems to be neither - seems strange to me - should feel at least some pressure, I think. Tried the same on a relative new Civic (15K miles) and there is some gas pressure indeed. Could it be a clogged PCV/breeder box?
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