Mysteriously using oil

[MSharp71635]

Has anyone ever heard of oil mysteriously disappearing from these? We have a 08 tahoe. Doesn’t smoke from anywhere, has good oil pressure but after a fresh oil change it gradually disappears. The first time I noticed this was when I changed the oil at the routine mileage one would change it at and it literally had a little over 2 quarts left in it.

 

[David Smith]

If yours has the AFM, that is probably the issue

 

[swathdiver]

Has anyone ever heard of oil mysteriously disappearing from these? We have a 08 tahoe. Doesn’t smoke from anywhere, has good oil pressure but after a fresh oil change it gradually disappears. The first time I noticed this was when I changed the oil at the routine mileage one would change it at and it literally had a little over 2 quarts left in it.

It's not a mystery. The engine is burning the oil if there are no external leaks. Poor quality oil will cause it to evaporate. The PCV system was redesigned in 2011 to reduce the amount of oil that was being ingested by the engine. There is also a cover in the oil pan that keeps oil from spraying onto the underside of the pistons/cylinders. Worn rings will also consume oil.

How many miles? How does the AFM operate on it? Has it been overhauled?

 

[MSharp71635]

A little over 120,000 I believe, no overhaul, still has the AFM unfortunately. I did research the valve cover issue though and plan to do that ASAP. I’ll look intobthe oil pan fix as well, thank you so much

 

[swathdiver]

A little over 120,000 I believe, no overhaul, still has the AFM unfortunately. I did research the valve cover issue though and plan to do that ASAP. I’ll look intobthe oil pan fix as well, thank you so much

Is the motor regularly spun up to 3000+ rpms? Any smoke upon start up?

 

[MSharp71635]

Is the motor regularly spun up to 3000+ rpms? Any smoke upon start up?

I’m not sure I follow on the regularly spun up to 3,000 RPM, but no smoke on start up.

 

[swathdiver]

I’m not sure I follow on the regularly spun up to 3,000 RPM, but no smoke on start up.

When accelerating from a stop, does the engine regularly turn more than 3,000 rpms in 1st gear to get up to speed?

 

[MSharp71635]

When accelerating from a stop, does the engine regularly turn more than 3,000 rpms in 1st gear to get up to speed?

Mmmmmm I honestly can’t say for certain on that. I would say borderline 3000 possibly. Seems kinda of high for me I can say that but it’s primarily my wife’s car. She may get it up to that on acceleration.

What is the issue regarding that out of curiosity?

 

[MSharp71635]

Also, I just bought the replacement valve cover so i will be installing that tomorrow.

 

[swathdiver]

Mmmmmm I honestly can’t say for certain on that. I would say borderline 3000 possibly. Seems kinda of high for me I can say that but it’s primarily my wife’s car. She may get it up to that on acceleration.

What is the issue regarding that out of curiosity?

The higher folks wind them up, the more blow by through the PCV system which gums up the throttle body, intake manifold, etc. and of course uses up oil.

When my wife drives the truck, it comes back empty with the mileage tanked because she likes the way it accelerates. I don't often hit 3000 and use no oil between changes so far.