L99 Using Oil

[chuckit]

Okay. I have a 2011 SS, L99, approx. 135,000 miles that is using oil at a pretty high rate. I am just wondering what the issues are that would cause this. I added 2 quarts a month ago and now it is about a quart low. Definitely not leaking. Exhaust does not smoke. Scratching my head on this one.

Any help would be greatly appreciated.

I tried searching for this issue and did not find anything.

TIA

[Indian_Mack]

I would change the pcv valve and install a catch can. Probably slowly burning off that way.

If that doesn't help, do a compression test to make sure it's not the head gasket.

[TheBrightSide]

Originally Posted by Indian_Mack

I would change the pcv valve and install a catch can. Probably slowly burning off that way.

If that doesn't help, do a compression test to make sure it's not the head gasket.

I did a compression test on my LS3 and it was fine. I even replaced the valley cover, with the built in PCV system, which looked fine as well… If I don’t have a catch can installed, the intake manifold/throttle body fills up with a bunch of engine oil; as in it will just collect through the valley cover PCV and then just pool up inside the manifold…

I have to dump my oil catch can every 2-3 weeks, depending on how often I drive (is my current daily driver). I even had a custom mounted oil catch can setup at one point, and it was further away and the can sat by the firewall, next to the ABS module; yet it still sucked up just as much engine oil, if not more… I ended up installing some check valves/in-line PCV valves, to slow down the oil blow-by.

It doesn’t even seem like there’s anything blowing out of the oil filler cap area, if you’re trying to check that, while the engine’s on and running… I’m kinda lost at this point, although I haven’t done a leak down test; just not sure if that would even be any more beneficial than the compression test that I did (which yielded pretty okay/within range results).

[TheBrightSide]

The 2009+(?) GM LS V8 engine valve covers, had a revision where they re-designed the driver side valve covers’ baffles and baffle plates. This helped the PCV port to not suck up and spit out so much engine oil, through the hose and into the intake manifold…

You might want to check your engine valve cover on the driver side, and maybe replace it with an updated one if possible. The newer ones have a square cutout, whereas the older valve covers have a circular cutout on the baffle plates. Might wanna install an engine oil catch can and see if that’s the issue with the PCV…

[InFiD3ViL]

PCV 'valve' in our cars is in the valve covers.

[FASTFATBOY]

GM allows 1 quart of oil consumption per 2000 miles of normal driving.

All high mile LS engines use oil.

[morepowerjoe]

Originally Posted by chuckit

Okay. I have a 2011 SS, L99, approx. 135,000 miles that is using oil at a pretty high rate. I am just wondering what the issues are that would cause this. I added 2 quarts a month ago and now it is about a quart low. Definitely not leaking. Exhaust does not smoke. Scratching my head on this one.

Any help would be greatly appreciated.

I tried searching for this issue and did not find anything.

TIA

Easy way to check for blow by. Take the oil filler cap off with the engine running and put your hand over the fill hole and there should be a slight vacuum. If there is any kind of pressure to it or it doesn't have a slight vacuum, then you probably have blow by from the rings.

[TheBrightSide]

Originally Posted by morepowerjoe

Easy way to check for blow by. Take the oil filler cap off with the engine running and put your hand over the fill hole and there should be a slight vacuum. If there is any kind of pressure to it or it doesn't have a slight vacuum, then you probably have blow by from the rings.

Yeah, in my case with my post above, I didn’t have vacuum from the oil filler area at all whatsoever. Still have yet to figure out what it is…. When I first got the car, I even ran a few motor flush formulas, in the case that I had some sticking piston rings. But then again, my engine ran perfectly fine all the way to redline all the time, so I knew it wasn’t sticking rings.

I would certainly install a revised driver side engine valve cover, since the L99 engines don’t run the PCV through the engine valley cover, like the LS3 engines do. That is, unless you have a DOD/AFM delete and maybe keep the PCV through the driver side engine valve cover, and no switch to the LS3 PCV engine valley cover. For the time being, I would highly advise setting up an oil catch can, just to see how much oil is actually being blown by, through to the intake manifold…