Knock when cold

[Marky Dissod]

I’m at about 4K on Mobil1 full synthetic. I typically go about 5k on full synthetic, so about another month.
However, I have been noticing that my oil pressure has been relatively low. I checked my oil, I was down a full quart. Just to be good, I added a quart.
I’m still going to change it shortly. The pressure seems to be better, mostly, but does drop at different times while driving.

Think maybe you should change your oil and filter before your engine consumes any. Try 4500 miles?

... do the manifold bolts make that big of a difference? I had a mechanic replace both manifolds.
I kept getting leaks, he kept tightening the bolts, put in new gaskets tried different grade bolts with high heat lock tight. But the leak keeps coming back.

Actually, they do. An exhaust manifold leak makes the engine run rich. O2 sensors are fooled by atmosphere in the exhaust, and add fuel.
Some of that added fuel gets past the piston rings into the oil, diluting it, making it easier for that motor oil to be consumed.

Your mech needs to try a more clever tightening sequence.

 

[donjetman]

I’m glad I happened onto this thread. My ‘11 Denali with 125k has had me very concerned lately. Granted it has been quite cold lately in northern Illinois, but the slap has been very loud on cold starts and tends to take 4-5 to go away. I’m at about 4K on Mobil1 full synthetic. I typically go about 5k on full synthetic, so about another month. However, I have been noticing that my oil pressure has been relatively low. I checked my oil, I was down a full quart. Just to be good, I added a quart. I’m still going to change it shortly. The pressure seems to be better, mostly, but does drop at different times while driving. Lastly, do the manifold bolts make that big of a difference? I had a mechanic replace both manifolds. I kept getting leaks, he kept tightening the bolts, put in new gaskets tried different grade bolts with high heat lock tight. But the leak keeps coming back. Any thoughts would be greatly appreciated.

Oil consumption, has your Denali had this GM Technical Service Bulletin done?
https://f01.justanswer.com/ebrock63...il+Consumption,+MIL+ON,+Engine+Runs+Rough.pdf
I did it 6+ yrs ago when we purchased our Denali, no oil consumption since
Here the thread w/pics: https://www.tahoeyukonforum.com/thr...tor-oil-consumption-tsb-10-60-10-008m.108493/

 

[charkmapman]

Think maybe you should change your oil and filter before your engine consumes any. Try 4500 miles?Actually, they do. An exhaust manifold leak makes the engine run rich. O2 sensors are fooled by atmosphere in the exhaust, and add fuel.
Some of that added fuel gets past the piston rings into the oil, diluting it, making it easier for that motor oil to be consumed.

Your mech needs to try a more clever tightening sequence.

Manifold bolts have tightening sequence and a torque value. You should not keep tightening willy nilly. Oil consumption linked to valve cover known issue. You could add oil scavenger "catch can " to PCV port on top of valve cover. Inexpensive on amazing. Noise is most probably piston slap. Run only recommended weight and SAE type oil recommended by GM either on oil filler cap or manual. VVT motor depends on correct oil tom operate. Check oil bypass cover just above oil filter is not leaking. Also Main bearing securing bolt above starter is known to leak oil .Clean threads and apply Aviation form a gasket to threads. tighten to torque specs.

 

[donjetman]

VVT motor depends on correct oil tom operate.

Not

I've run 0-20, 5-30, 0-40, & 10-40 in our 6+ yrs and 70k miles of ownership of our 6.2L L92 w/VVT. These oil viscosities have made ZERO difference.