Excessive Oil Consumption Problem

[2020AT4]

I have a 2020 GMC Sierra AT4 that I got in 2019. Not long ago my instrument cluster dinged and alerted me that I was low on oil. I thought it was odd because I was still 2,000 miles early for an oil change. I called the dealership and scheduled an appointment, but unfortunately all they did was an oil change, they didn't investigate the problem to see what was causing it. I thought that was kind of weird because just doing an oil change wasn't going to fix it, just like if someone comes in with a flat tire, do they just pump it back up with air and call it good or do they try and find the problem, like, is there a nail stuck in the tire, pull the nail, and patch the hole. I hoped it was a 1-off, but unfortunately last week it did it again - low oil 2,000 miles before it's due for an oil change. This time I checked the dipstick and it was bone dry. There's no puddles under the truck anywhere I park, so it's not a leak in that sense. They filled it up to do an oil consumption test and I have to bring it in every 1,000 miles so they can see if it's burning too much oil. I'm still under warranty. It's a 5 year/60,000 mile warranty and I'm at 4 years and 53,000 miles. Strange thing is they billed me for the oil change even though it's part of their warranty diagnostic test. Has anyone else had this issue where their AT4 is burning through oil too much like this?

Edited October 12, 2023 by 2020AT4
additional info

[Grumpy Bear]

Which motor is this? 

[2020AT4]

10 minutes ago, Grumpy Bear said:

Which motor is this? 

6.2L V8

 

I suppose that would've been an important detail to include in my original post hahaha 

[Grumpy Bear]

1 hour ago, 2020AT4 said:

6.2L V8

 

I suppose that would've been an important detail to include in my original post hahaha 

 

Okay, so before it hit 50K it wasn't using any oil between oil changes of how long? 

[redwngr]

Or it was using oil, but not enough to turn on the low oil sensor?

 

Have driving habits changed?

 

How often does the dipstick get pulled to check the oil? 

 

Are you using a 7500 mile oci -- and sensor is going off at about 5500 miles? 

 

 

 

Edit: to correct spelling

 

Edited October 13, 2023 by redwngr

[2020AT4]

23 hours ago, Grumpy Bear said:

 

Okay, so before it hit 50K it wasn't using any oil between oil changes of how long? 

Oil change every 5,000 miles. I'm sure it was using oil, but not enough to trip the low oil sensor.

[2020AT4]

17 hours ago, redwngr said:

Or it was using oil, but not enough to turn on the low oil sensor?

 

Have driving habits changed?

 

How often does the dipstick get pulled to check the oil? 

 

Are you using a 7500 mile oci -- and sensor is going off at about 5500 miles? 

 

 

 

Edit: to correct spelling

 

Driving habits haven't changed. I was getting oil changed every 5,000 but since this started happening it's been every 3,000 the last couple times.

[Grumpy Bear]

6 hours ago, 2020AT4 said:

Oil change every 5,000 miles. I'm sure it was using oil, but not enough to trip the low oil sensor.

 

6 hours ago, 2020AT4 said:

Driving habits haven't changed. I was getting oil changed every 5,000 but since this started happening it's been every 3,000 the last couple times.

 

Four paths out of the crankcase. Leaks. PCV system. Valve guides. Rings. 

 

It would be strange to have the valve guides or seals compromised at this milage. Leaks would be most obvious. PCV valve is possible. Change it and give it an OCI to see if that helps. Most likely is low tension rings whose drain back is obstructed, or oil rings collapsed from varnish (fuel dilution) or carbon OR second ring (oil scraper) whose dam has carboned. 

 

Might wish to consider a UOA and we would be looking for fuel dilution in excess of say 2.5% and wear metals of aluminum and iron not conforming to the engine class and type. Short- and long-term fuel trims that do not come close to zeroing each other out. 

 

Given the milage and the warranty limits the consumption test will come up 'normal'. They call a quart in a thousand 'normal". Stinks, I know. Been there, have the Tee shirt and burned it already. You will get no help from GM. On the rare chance they do help it will be new pistons and rings in an un-honed bore and a story about it taking a few thousand miles to bed them in. Whatever. It will get you past the warranty, even the extend one, if offered. Will not solve the problem. 

 

You can rebuild the beast. You can get a crate motor. Both, on your dime.

 

If the UOA or trims show fuel dilution some diagnostics may find an injector or High-Pressure Fuel Pump seal leak. (HPFP). Fixing those issues may correct it providing the rings haven't varnished and collapsed. Something wear metals will show. A stuck ring will show elevated aluminum and iron. If just carboned the wear metals will be normal even if fuel is high. 

 

Okay if stuck rings then there is a GM top soak to free them. It works but is short lived. 

 

High Performance Lubricants has an ester-based engine cleaner that over time will free rings. Time is like 25 to 30K miles. Use mixed 5:1 with a good HDEO on short OCI's. Might even get worse for a few changes. Expect that. 

 

Root cause is shelf oils, even DEXOS licensed oils do not prevent deposits, ring deposits. They slow the rate of buildup but do not prevent it or clean them once there. Second cause is 0W20 oils in motors like this. Good for GM. Good for CAFE and EPA. Bad for owner operator and engine. 5W30 minimum. 5W40 better. 

 

IF you get them freed up without a rebuild the use something like HPL Premium or Red Line HP that contains and ester in enough quantity to be useful as a solvent. And VIS up a grade or two. 

 

If you are not successful freeing them up rebuild or crate motor, then start with these oils on 5K OCI's or whatever self oil pleases you on 3K or shorter OCI's and VIS UP.

 

You have questions PM me. But I won't debate it or justify this post. Do as you please.  

 

 

 

 

[SporkLover]

Here is a silly question.  Are you sure the dealership put in the correct amount of oil when doing the oil change?  Some assume 6quarts when 8 is needed. 

[diyer2]

Well................

No excuse for a low oil alert coming on. 

[2020AT4]

On 10/19/2023 at 8:35 AM, SporkLover said:

Here is a silly question.  Are you sure the dealership put in the correct amount of oil when doing the oil change?  Some assume 6quarts when 8 is needed. 

 I didn't go in the shop and watch over their shoulder to see if they were doing their job correctly. If they didn't, then they would've had to have made the same mistake twice since the low oil alert has come on twice now, each time 2,000 miles before it was due for an oil change.

Edited October 23, 2023 by 2020AT4
Spelling Error

[2020AT4]

On 10/13/2023 at 11:25 PM, Grumpy Bear said:

 

 

Four paths out of the crankcase. Leaks. PCV system. Valve guides. Rings. 

 

It would be strange to have the valve guides or seals compromised at this milage. Leaks would be most obvious. PCV valve is possible. Change it and give it an OCI to see if that helps. Most likely is low tension rings whose drain back is obstructed, or oil rings collapsed from varnish (fuel dilution) or carbon OR second ring (oil scraper) whose dam has carboned. 

 

Might wish to consider a UOA and we would be looking for fuel dilution in excess of say 2.5% and wear metals of aluminum and iron not conforming to the engine class and type. Short- and long-term fuel trims that do not come close to zeroing each other out. 

 

Given the milage and the warranty limits the consumption test will come up 'normal'. They call a quart in a thousand 'normal". Stinks, I know. Been there, have the Tee shirt and burned it already. You will get no help from GM. On the rare chance they do help it will be new pistons and rings in an un-honed bore and a story about it taking a few thousand miles to bed them in. Whatever. It will get you past the warranty, even the extend one, if offered. Will not solve the problem. 

 

You can rebuild the beast. You can get a crate motor. Both, on your dime.

 

If the UOA or trims show fuel dilution some diagnostics may find an injector or High-Pressure Fuel Pump seal leak. (HPFP). Fixing those issues may correct it providing the rings haven't varnished and collapsed. Something wear metals will show. A stuck ring will show elevated aluminum and iron. If just carboned the wear metals will be normal even if fuel is high. 

 

Okay if stuck rings then there is a GM top soak to free them. It works but is short lived. 

 

High Performance Lubricants has an ester-based engine cleaner that over time will free rings. Time is like 25 to 30K miles. Use mixed 5:1 with a good HDEO on short OCI's. Might even get worse for a few changes. Expect that. 

 

Root cause is shelf oils, even DEXOS licensed oils do not prevent deposits, ring deposits. They slow the rate of buildup but do not prevent it or clean them once there. Second cause is 0W20 oils in motors like this. Good for GM. Good for CAFE and EPA. Bad for owner operator and engine. 5W30 minimum. 5W40 better. 

 

IF you get them freed up without a rebuild the use something like HPL Premium or Red Line HP that contains and ester in enough quantity to be useful as a solvent. And VIS up a grade or two. 

 

If you are not successful freeing them up rebuild or crate motor, then start with these oils on 5K OCI's or whatever self oil pleases you on 3K or shorter OCI's and VIS UP.

 

You have questions PM me. But I won't debate it or justify this post. Do as you please.  

 

 

 

 

 

That's a lot of good information, but unfortunately it sounds like it's all going to boil down to that they are going to screw me out of the warranty. Correct?

[SporkLover]

Yeah sorry I wasn't suggesting that.  Some people are still in the old habit of checking oil pretty frequently like with every fill up.  Just thought that one thing could be eliminated if you did. 

[diyer2]

A lot of people should be glad I'm not the CEO of any car manufacturer because if I was and the low oil light came on I would void your drive train warranty. You've proven you don't care to me.

There is no excuse for not checking the oil. 

[KARNUT]

6 hours ago, diyer2 said:

A lot of people should be glad I'm not the CEO of any car manufacturer because if I was and the low oil light came on I would void your drive train warranty. You've proven you don't care to me.

There is no excuse for not checking the oil. 

I don’t believe that. I’m old enough to have needed to check oil every gas fill. I’ve had at least 20 trucks and many more cars. Most were high performance or modified that way. Since at least the nineties I’ve only had two vehicles used oil. They would have made it to oil changes without damage. I got used to not needing to check the oil. Modern vehicles have sensors for everything. A qt low check oil light should be a no brainer. I have vehicles currently two are approaching 150K one 200k. They don’t burn a drop. I can picture people at gas stations dressed to go to work trying to reach the dipstick, especially the ladies. They have a sensor for the brakes, the oil pan is more important. No today I don’t believe you should have to check your oil.