Smoke out the back of a 2020 6.2 Denali

Shiva · July 1, 2020

So after the dealer FINALLY fixed my oil leak (bad lower oil cooler connector) noticed driving down the highway and occasionally i was spewing a blueish/grayish white smoke from both of my exhaust. Only for 1 or 2 seconds at a time...in short bursts. I only have 1500 hundred miles on the damn truck.

It's only happened about three to 4 times so far as it's not consistent. I can't seem to replicate it. Tooki it to the dealer and they didn't do anything. No DTCs showed up either.

Fearing a head gasket leave I've completed the coolant block test, looked for creamy looking oil myself...Everything seems normal. I did check the oil level and it seemed way overfilled. Changed it a couple of days ago.

I could swear it was like over 2 quarts overfilled. So I put 8 fresh quarts in and a new filter. Don't think I've driven it enough to see the smoke again...but it seems completely random.

Could 1500 miles overfilled cause any permanent damage? I notice the smoke only after the oil connector repair. Maybe the dealer topped the oil off and overfilled it during the repair?

chadman · July 1, 2020

Highly unlikely it would cause any issues. Anything is possible, but it would seem really strange it would be two quarts overfilled. They would have lost some oil from the cooler repairing the leak, so it would be logical they checked and adjusted. On modern engines, overfilling can cause smoking issues as there will usually be excessive oil splashed up on the oil rings. I would not be to terribly concerned.