I have a recently purchased 2011 Yukon Denali 6.2L with 316,000 km. When I bought it I noticed once in awhile it would let out a puff of smoke on start up. I installed an oil catch can, which filled up rather quick, and didn’t notice the smoke thing happening anymore. Recently we made some longer road trips though and it seems after a few hours of driving once it cools it let’s out a puff of smoke and then it’s good again until we make a longer trip again. I have searched forums but haven’t found anything that sounds similar to this. Other than that it runs great and oil pressure is consistently just under 225 kpa when warm

 

Sounds good to me !!!

 

well I guess it will help keep the mosquitoes away next summer

 

Considering the miles on the engine and not knowing the maintenance history, do you think it could have worn valve stem seals?

 

I was wondering about that but thought I would see the smoke more consistently

 

I’m back with an update on this problem. After using for about a month doing quite a few long road trips (my son plays hockey) and making sure to empty the catch can regularly the smoke problem stopped. So I decided to change the valve cover to the updated one rather than continuously emptying the can. We made a 7 hour road trip yesterday and I just checked the can, no oil but it was half full of what looks like chocolate milk. Previously there was always a bit of moisture with the oil but this does not look good to me. I’m wondering if I have a coolant leak somewhere getting into the oil

 

if its just in the catch can it could be moisture from the pcv system due to cold ambient temps. If you get oil into the air cleaner/resonator box the truck may have excess blowby gases. Is the truck burning oil? any deposits on the spark plug?

 

it seems to be just in the catch can. I left the contents outside in below freezing weather after it separated into a semi clear liquid and small layer of foam and the liquid froze so looks like just condensation. Thank God it’s not coolant. Looks like the updated valve cover is doing its job, basically no oil and before a trip like that would have been a full catch can of oil