1995 Chev 5.7l Using Oil, No Smoke Or Leaks

[JWW8]

My truck has 100K miles on it. I just had new valve seats, PCV, and intake manifold gasket installed. A compression check now reads 130-145 lbs on all 8 cylinders. The engine runs good and has plenty of power. There is black soot in the tailpipe but it is powdery not sticky. No visible leaks or smoke. It is using about a qt of oil every 200-300 miles. What could be causing the high oil consumption?

[cliobogger]

holy crap, 1 qt to every fill up is a lot...and no smoke or leaks you say...how long ago did this start?

[JWW8]

holy crap, 1 qt to every fill up is a lot...and no smoke or leaks you say...how long ago did this start?

 

It has been using this much oil for almost a year. That is why I had the valve seats replaced and manifold gasket replaced and complete tune up.

[ChevyTech77]

Valve seats or seals?

 

These engines were known for valve guide issues but 200-300 miles to a quart and you should be fogging the place down, wherever you drive. Not to mention that thing should be fouling spark plugs too. Do a cylinder leakdown test to confirm real stability in the cylinders.

[cliobogger]

yeah, you should be smoking the hell out of everything.

[donberry]

as everyone else said - have u looked under the truck after it has been sitting ? Maybe a hole in the oil pan. Tough to imagine using that much without it smoking pretty good

[exracer]

I have to agree with a oil leak...big chunk of cardboard under engine and let her run for a while....oil pans are usually a problem

[GMstrong]

I have the same problem but mine only leaks when you warm it up and take it for a spin then shut if off.Im not exactly sure whats causing mine either i think its the rear main but im not positively sure since its way to cold to get on my back and get underneath of her.

[exracer]

for what its worth..maybe next time try a oil specified for higher mileage engines,,,,have personally seen this stop a intake leak on one 305 engine and nearly eleminated a rear main leak on another,,,,doesnt hurt to try at your next oil chance

[JWW8]

Thanks for the replies. The oil pan does not leak. There is no oil under the truck and it does not smoke. Leak down test was good. The PCV is new and is not after-market. I am at a loss as to where this much oil could be going. Plugs are clean as well - no oil fouling.