Is Your Gmt-900 Truck Or Suv Using Oil

[MaverickZ71]

Well I figured I was imune, but I'm not LOL. My wife's 2008 Tahoe with 130K miles had no oil showing on the dipstick!! It was 1.5 quart low at 30% OLM. I read the first 100 posts of this thread and then skipped to,the end. Was there ever a discussion of cause? Do the inactivated cylinders suck in oil due to closed valves (high vacuum) and then the rings carbo up and then don't seal well? That's the only thing I can think of. Or is there some other mechanism leading. To,the oil consumption?

If I install the Range, will the engine clean up on its own?

You woulda been better served to read the last 100 posts, or go back and read them all, in order to learn about all the associated problems and what to do. AFM is a flawed system built with cheap parts and indifferent tolerances. Most important thing is to turn off AFM via a Range V8 module or PCM tune, and make sure you have the revised GM parts installed as per the TSB posted on here. An oil catch can may help as well. Then If you are running synthetic oil, consider running conventional or semi-synthetic, and/or a heavier viscosity. Clean your piston rings and spark plugs as described on this topic. And check your oil at every fill up. Edited July 24, 2017 by Maverick Z71

[Jsdirt]

Well I figured I was imune, but I'm not LOL. My wife's 2008 Tahoe with 130K miles had no oil showing on the dipstick!! It was 1.5 quart low at 30% OLM. I read the first 100 posts of this thread and then skipped to,the end. Was there ever a discussion of cause? Do the inactivated cylinders suck in oil due to closed valves (high vacuum) and then the rings carbo up and then don't seal well? That's the only thing I can think of. Or is there some other mechanism leading. To,the oil consumption?

If I install the Range, will the engine clean up on its own?

There's a lot of theories floating around out there, but the bottom line is, GM tried to save a buck and screwed up! Any engine builder that built an engine like this would be out of business.

 

TOTALLY UNACCEPTABLE.

 

I just learned from my last oil analysis that my cam bearings and cam are wearing out at an alarming pace. Been seeing lots of valve train issues on these engines from '07 on up. Broken valve springs, wiped out lobes, stuck AFM lifters, & prematurely worn out bearings.

 

A fine job they did for us being loyal customers.

Edited July 24, 2017 by Jsdirt

[need-for-speed]

You woulda been better served to read the last 100 posts, or go back and read them all, in order to learn about all the associated problems and what to do. AFM is a flawed system built with cheap parts and indifferent tolerances. Most important thing is to turn off AFM via a Range V8 module or PCM tune, and make sure you have the revised GM parts installed as per the TSB posted on here. An oil catch can may help as well. Then If you are running synthetic oil, consider running conventional or semi-synthetic, and/or a heavier viscosity. Clean your piston rings and spark plugs as described on this topic. And check your oil at every fill up.

You woulda been better served to read the last 100 posts, or go back and read them all, in order to learn about all the associated problems and what to do. AFM is a flawed system built with cheap parts and indifferent tolerances. Most important thing is to turn off AFM via a Range V8 module or PCM tune, and make sure you have the revised GM parts installed as per the TSB posted on here. An oil catch can may help as well. Then If you are running synthetic oil, consider running conventional or semi-synthetic, and/or a heavier viscosity. Clean your piston rings and spark plugs as described on this topic. And check your oil at every fill up.

Thanks. I'll go back and read the ones I missed. I only run dinosaur oil in the wife's Tahoe.

 

just changed the oil. I will get an analysis in a couple thousand miles.

 

I also have a 2008 Silverado w/ 5.3. It only has 22K miles. Looks like I'll be buying two Ranges and checking the oil much more often.

Edited July 24, 2017 by need-for-speed

[need-for-speed]

p.s. Did GM improve the design on the latest gen? We are probably going to sell the 08 Tahoe next year and get a 2018.

[Jsdirt]

Sadly, the folks who spent $50 GRAND on a new one won't know until it's just out of warranty.

 

The issue with dino oil in these engines is, if left unchanged for too many miles, will be more likely to plug up the screen under the pressure sender with crap that will make the gauge read very low - it'll get your blood pressure up there when you see it, and throw a light (P0521).

Edited July 24, 2017 by Jsdirt

[need-for-speed]

The AFM shield deflects and helps stop oil mist/vaporization which has a greater chance of getting sucked out by the pcv system.

Will the oil catch can do the same thing? Possibly even better?

[Colossus]

Nope.

[Jsdirt]

The shield was a band-aid by GM to try and save their asses. Few people reported it working, and those that did were back in the same boat just a year or so later.

 

Just enough to get you out of warranty ...

 

I've had a catch can on mine for a couple years now. Still burns oil if I use cruise control while towing, and let it scream to 5 grand on hills. If I go easy on it, the consumption is tolerable. That to me screams piston rings, no matter what GM tells me.

[need-for-speed]

Thanks again for the replies. For my 2008 Silverado- it's still under GMPP extended warranty. Do y'all know if they will install the oil pan and valve cover mods without the oil consumption test? Or would it have to fail the test first?

[robroy]

Thanks again for the replies. For my 2008 Silverado- it's still under GMPP extended warranty. Do y'all know if they will install the oil pan and valve cover mods without the oil consumption test? Or would it have to fail the test first?

 

 

I took my Sierra in for something unrelated and the dealer asked if I had the time to wait around to have the heads replaced (I did not, but I made time for that!)

[need-for-speed]

Thanks.

 

Hmmmm, haven't seen anything yet on head replacement, although I must admit, I've only read about 40% of this thread so far. I've seen references to, rings and pistons, driver side valve cover and oil pan. Did they say why they replaced the heads?

[Jsdirt]

The heads aren't the major problem (cheap valve springs are, but that's a discussion for another day) - I believe the problem lies in cheap and/or poorly designed AFM lifters, cheap/poorly designed piston rings and/or sub-par quality control.

 

My suspicion is they're running their tooling until the last possible minute to extract the most for their money. So, when the tooling wears out, you'll have thousands of engines that are out of spec, or on the ragged edge of being out of spec, and will become oil burners much sooner than they should. They change the tooling, and all is well for thousands of units until it wears out again. This explains the hit or miss nature of these problems.

Edited July 25, 2017 by Jsdirt

[Northman]

1200 miles. Checked oil this am and it was just a little under the full mark. Oil pressure still strong. Looks like its working. My wife is taking it to MN this weekend to bring my grandson back to his mama. Its about 600 miles round trip. I'll check it when she gets back and let you know what it says.

Well the oil was down about a 1/3 of a quart after this trip. Drove to Fargo this past weekend and checked it. Its was more than a quart low. So apparently the 5W40 slows the oil loss up to about 2000 miles then its back to normal loss levels (quart every 500 to 700 miles) Mileage is now about 104K. I think I'll change it at 3000 miles but this time I'll try conventional 15W 40 oil and see what happens. Anybody know if this is not a good idea? Too thick?

[Jsdirt]

If it were me, I'd run 20W-50 if I were using that much oil.

 

The way I see it, the engine is pretty much junk anyway. Not going to hurt much running a heavier oil. I saw a big decline in piston and ring wear metals in my oil analysis by switching from 5w-30 to 10w-30. Even though the "10" is rating it's cold flow properties, it's an overall higher viscosity oil, which helped alot in my case.

 

I just wish I had started doing this right out of the gate

[robroy]

Thanks.

 

Hmmmm, haven't seen anything yet on head replacement, although I must admit, I've only read about 40% of this thread so far. I've seen references to, rings and pistons, driver side valve cover and oil pan. Did they say why they replaced the heads?

 

come to think of it, it was probably the valve covers. That little occurrence was maybe 5 years ago, so my memory is a little fuzzy.