Welcome to the Corvette Forums at the Corvette Action Center!

C6 LS2 burning large amounts of oil

Andric Hays

New member
Aug 13, 2015
Hello I've got a 2005 C6 corvette with an ls2 engine, I figured I would reach out to the forums in hopes I might find someone who might be able to help diagnose an oil burning issue I've been having over the past year (it has gotten progressively worse). I would go to a shop but there are no reputable shops in the area that I trust to do a better job than myself (sad but true). I will break down my symptoms in chronological order,

Car was burning oil at 2quarts every 800 miles no smoke during idle or deceleration but some during acceleration.

I performed a valve stem swap with felpro seals but I got the same amount of oil burn after ( during this swap I noticed black particles from the previous valve stem seals which had degraded)

I then performed another valve stem swap using GM parts, I cleaned every square millimeter during this swap and checked wiggle on the guides (I was using the pressurized cylinder method I'm not sure if that affects wiggle).

At this point in time I assumed it to be rings so I put upper cylinder lubricant into my gas and 3 cans of sea foam into my oil let it idle for 30 minutes and drove it around for 2 hours. I then swapped a new filter and new oil into the engine.

My intake manifold had tons of dirty oily gunk built up in it and the tubes running into it were very oily so I did a valley cover swap and cleaned all the area off, I used new intake manifold gaskets although they looked new. The evap purge solenoid was totally locked up and all of its hoses were old and the contacts cracked easily. So I swapped out all the tubes and hoses pertaining to the pcv system and the evap purge ventilation system. I also cleaned the crud out of the throttle body because I was getting some delay at idle. Then I unplugged the radiator fan and tried to reseat the rings assuming I had cleaned the engine out, this caused a boil over in the engine coolant once I checked the area to allow it to cool down without added pressure. It was then I discovered that my thermostat was totally busted, so I took it out. These fixes increased performance dramatically.

However oil burn is still a major factor, I am burning oil at the same rate (higher actually accounting for the spirited use of the engine). I get some hesitation at around 3000 rpm but if I press the gas a little further it powers over it and begins acting like it should all the way up to 5000 rpm (I didn't press it much further). And the car pulls like a mad man. However I do get a few misfires at random times between 3000-4000 rpm but not above that range.
I am getting no oil inside any of the evap tubes, pcv tube however I do find some oil on the tip of the evap tube connected directly to the intake manifold but not the other end of the tube (strange).

If you've got literally any ideas as to what else it could be please let me know.
How many miles are on this engine?

What's been its primary duty cycle?

What's been its oil drain intervals?

What kind of oil?
How many miles are on this engine?

What's been its primary duty cycle?

What's been its oil drain intervals?

What kind of oil?

approximately 2500rpms (I don't race it it's been a daily)
it used to be every 3000 miles now it is much more frequent ha
mobil 1 full synthetic 5W-30, I used Castrol magnetic for additive once or twice. But I use Mobil 1 almost always.
Run a compression and cylinder leakage tests and post the results.

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom