Evidence?
We bought our 07 Yukon 6.2L Denali one yr ago. We have put 16,000+ miles on it. We have done 2 oil and filter changes(8,000 miles ea) and 2 UOA, (used oil analysis). Each time I have cut the oil filter open and have found black carbon/gunk/crud at the bottom of the pleats(See pics in posts #s 1 & 27 here). I've asked myself if my extended oil change intervals are causing this stuff or is the oil I'm using, Mobil Delvac 1 ESP 5w-40, actually slowly cleaning up the carbon/gunk/crud that's stuck on the guts of the engine from it's prior life? I think I have my answer.
The oil I'm using is cleaning things up. I came to this conclusion by taking the new improved driver side valve cover off for inspection(see pic below). It is still as clean as new(the evidence). It was installed 16,000+ miles ago before we started using this oil. Here's a pic from the other day.
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The pic below is from a yr ago when I take the original VC off and installed the new improved one.
View media item 27448
You won't catch me adding any product(s) to my oil that might quickly break the gunk loose for fear of plugging things up.
You may remember we bought this 07 Yukon 6.2L Denali Oct. 2018 w/130k miles off a used car lot without any mx history. We figured out real quick that it burned and leaked a lot of oil. But, it had good oil pressure and drove like a dream. I am a DIYer. I fixed the leaks by changing the rear main seal and oil pan gasket. Cured the oil burning by installing the new improved driver side valve cover and performing TSB 10-06-01-008M. I made a lot of posts here w/pics last Nov & Dec when I was doing all this work. There is a lot of gunk/crud built up inside the engine from its prior life. I also installed a remote engine oil bypass filtration system that utilizes an Amsoil EaBP90 spin-on filter.
I cleaned and reinstalled the spark plugs, installed new wires, installed a catch can. Before I fixed everything, the catch can was catching about 1oz of oil every 100 miles. Now it catches 1 oz every 6000 miles. We don't need to add oil between 8,000 mile oil/filter changes.
We love our Yukon
What do ya think?