I really dont want to start a war so I will explain the problem that I was having..
I do alot of driving...My truck has alittle over 160k on it.. Its a 2007 GMC Sierra SLT nbs 5.3.. I Love my truck.. I"m hoping to get 200k on it before I trade.. but for as long as i can remember it was using oil...about a quart every 4k.. I started using mobil 1 I think after or around 20k miles.. I always change my oil every 5k-6k miles.. I dont care what anyone says 5k-6k is perfectly fine if your using synthetic..
Anyway back to my oil consumption issue..It never got worse..My add oil light would come on it after every 4k.. but recently I noticed after coasting down a long long hill at least 1\2 a mile with my foot completely off the gas the whole time & when you stepped back on the pedal the exhaust would blow out blue smoke....If you coasted a mile or more it would leave a 40-50 foot long trail of blue smoke when you stepped back on the gas...then it would clear up after the oil burned out of the cylinders that were turned off while coasting....
You could start the truck up @ -20 & rev it up..No smoke...It would NEVER smoke any other time..
Went on a road trip awhile back & our freinds that were following us called & said what on earth is wrong with your truck!!?!
Otherwise I never would have noticed....Dealership said it was normal to use oil..I said is it normal for it to Smoke???? Kinda ticked them off by saying that but I never got anywhere..
Was told by my mechanic it could be a leaking valve guide seal..Well when I first start the truck in the morning it should puff out some blue smoke..That usually means valve guide seals... But it wasnt doing that..
I wondered if somehow with it in 4cyl mode if it was pulling oil up past the rings or maybe pulling it in else somewhere else..
Bought a Programmer & turned off my AFM..over 2500 miles so far now & oil hasnt budged on the dipstick..Right at the full mark... & no smoke after coasting 1\2 a mile or more..
I may never know exactly why it was pulling oil into those cylinders but what I do know is my truck isnt using anymore oil...
Edited by GMC Yukon XL, 19 March 2010 - 05:46 PM.