Is Your Gmt-900 Truck Or Suv Using Oil

[diyer2]

Thanks !!!

I missed that in the manual.

I was checking it cold.

[Evan Snyder]

2007 Sierra Z71 AFM 5.3 129K miles mostly highway to and from the jobsites. 2 oil changes ago I ran a quart of Lucas Oil with 5 quarts of Pennzoil 5w30 and the last oil change it seemed to have used less. Some mornings I hear some piston slap on startup but it goes away pretty quick. oil pressure is still solid.

[AJO07]

09 ccsb, 5.3l with VIN code M. i believe this is the Al block. using ~1 quart in 5000miles. went through the pvc breather/ valve cover/ fouled plugs routine at about 40k. Blackbear tune at about that same same, including disabling the afm. oil consumption improved slightly but remains at ~.75 quart per 5k. no formal oil consumption test but am planning to do one. using mobil 1 syn and lucas oil syn oil stabilizer. 65k miles on the truck currently.

[Colossus]

A qt every 5000 miles is not bad at all...

[wesd]

2011 5.3 CC here just crossed 54k miles. No oil usage to date, BUT...

 

Last month truck had thick blue smoke out of the tailpipe on warm start. Twice in two days, and hasn't done it since. Oil level is fine.

 

Noticed that anytime its in V4 I'm getting serious detonation - that at any load, it will kick it back to V8 almost instantly. Also has started idling rough.

 

Going to get the Range device, but in the meantime, 5/100k warranty just expired and I want to ask the dealer to do a top engine clean and investigate? Any suggestions?

[studly]

 

 

Last month truck had thick blue smoke out of the tailpipe on warm start. Twice in two days, and hasn't done it since. Oil level is fine.

 

Last month truck had thick blue smoke out of the tailpipe on warm start. Twice in two days, and hasn't done it since. Oil level is fine.

 

Thick puffs of smoke on startup is when my problems started.

Get that Range device to keep your engine in 8-cylinder mode.

[Jsdirt]

....

 

Going to get the Range device, but in the meantime, 5/100k warranty just expired and I want to ask the dealer to do a top engine clean and investigate? Any suggestions?

 

Range works great - I've got one in mine.

 

As for the dealership, I'd advise against that. Your warranty expired - no need to go there. The prices are high, and I have yet to see a dealership with top-notch workmanship. Everything is rushed, and billed at top dollar. Find a reputable local garage and go there. You'll thank me later.

[Colossus]

If you want to run an additive, I'd recommend this. https://www.bgprod.com/catalog/engine/bg-epr-engine-performance-restoration/ I don't usually like running additives, however- BG has been around a long time and seems to have a good track record. I ran BG44K in some older fuel injection vehicles at the recommendation of my auto repair facility, and I was satisfied with the results.

[Jsdirt]

Same stuff the dealer uses to do the decarboning procedure on the GDI engines. Stuff actually works, unlike autoparts store crap.

[pezboy]

2011 5.3 CC here just crossed 54k miles. No oil usage to date, BUT...

 

Last month truck had thick blue smoke out of the tailpipe on warm start. Twice in two days, and hasn't done it since. Oil level is fine.

 

Noticed that anytime its in V4 I'm getting serious detonation - that at any load, it will kick it back to V8 almost instantly. Also has started idling rough.

 

Going to get the Range device, but in the meantime, 5/100k warranty just expired and I want to ask the dealer to do a top engine clean and investigate? Any suggestions?

 

Smoke on start up on my 09 Tahoe at 50,000 miles is where my troubles began. I believe the dealer cleaned the engine out per GM instruction. A couple of months later at startup I had no oil pressure. The dealer said it was a spun bearing and they replaced the engine under warranty. I think it had to do with AFM myself.

[Northman]

Put in a bottle of motor medic and drove it about 70 miles then changed the oil. (I did this a couple of times ) I quit using Mobil 1 and switched to the cheap Walmart brand. I rarely smokes now and burning cut in half. Not sure why. Maybe somebody here has a theory?

[Cowpie]

I had oil eating issue with a 2006 Cadillac CTS 3.6 I got a year ago with about 52K miles on it. Did a few 1000 mile oil changes, using Amsoil Engine Flush at each change and ditched the M1 5w30 recommended by GM and started using Pennzoil 10w30 conventional (it has the GM 6094 rating recommended in the manual). Oil consumption dramatically decreased and engine runs better than ever. Even will bust the EPA highway mpg rating occasionally.

Edited March 22, 2017 by Cowpie

[Northman]

I had oil eating issue with a 2006 Cadillac CTS 3.6 I got a year ago with about 52K miles on it. Did a few 1000 mile oil changes, using Amsoil Engine Flush at each change and ditched the M1 5w30 recommended by GM and started using Pennzoil 10w30 conventional (it has the GM 6094 rating recommended in the manual). Oil consumption dramatically decreased and engine runs better than ever. Even will bust the EPA highway mpg rating occasionally.

Exactly! I believe the smoke at start up and the oil burning are related to sludge buildup and the use of synthetic oils (Mobil 1 in my case and yours apparently).

 

Those with smoking 5.3's should try flushing and a few short term oil changes then switch to conventional oil. That seems to help tremendously. Not sure why unless it frees up the stuck rings thus reducing blow by?

[Cowpie]

I chose the Pennzoil 10w30 conventional because of its reputation for cleaning up engine internals and the fact that the Petroeum Quality Institue of America tested it and found it had an exceptional additive package and even out did many full synthetics in NOACK performance. And at around $15 for a 5qt jug at my local farm and home store, a good value.

Edited March 24, 2017 by Cowpie

[Podor]

From what I understand, the oil consumption issues are due to the rings seize on the AFM cylinders because of lack of maintenance and the conventional oil not holding up over time. GM switched to the Dexos full synthetic, lower viscosity and 8 qt + capacity to minimize the problems that the gen 4 5.3 had. My wife's '07 had the slugs replaced about 15k before we bought it. I run Valoline full synthetic and change the oil every 4500 to 5000 with no issues. I did disable the AFM.

 

There is a TSB on the driver's side valve cover allowing oil to get sacked into the Pcv vacuum line. Ours smoked up the garage on cold startup before we changed it.