L87 Recall - Oil Changed - Engine & Fuel Economy Issue

[Vinnoto1]

Hello All,

Just visited my local dealership and had my 22 XL checked for the recall and ended up with the new heavier weight oil and extended warranty.

I couldn't be more disappointed with the performance of the engine as it now feels sluggish to accelerate, fuel economy has dropped roughly 30% and there is no way this baby is still outputting 420 BHP on the 6.2L

Yes, I know the heavier weight oil creates more drag/friction on the motor. But the difference is noticeable and unacceptable IMO.

Anyone else get the oil change and experiencing this issue?

 

[WalleyeMikeIII]

Either you have an issue, or it is in your head.

I have had 0W40 in my 6.2 since I passed the inspection mid June.

I reset the Trip 2 trip odometer at that time, I am averaging exactly the same MPG over the past 2000 miles as I averaged over the initial 38000 miles (I had never reset Trip 2).
Otherwise, my ride is all the same as it always was.

Now, that said, could the dealer have bungled something up, possibly, but would think a Check Engine Light would be on if something like a spark plug wire was removed, etc....Got any Buddies with a Yukon, go drag race them.

Recall, your engine is naturally aspirated. When the temps go up, and the humidity goes up, there is a performance loss; same thing happens in boating, to the point where some people i know have a different pitch prop for cool weather vs hot. 30% loss in fuel economy not so likely though.

 

[jfoj]

I have not had 0W20 engine oil in my truck since 544 miles and my truck is a 2025 with a July 15, 2024 engine build date so it is not within the recall window. I currently have 9,000 miles on the truck. Just took a 350 mile trip the other day in 105F weather and ended up with 18.5 MPG driving the truck hard, 80+ at times and having to pass a bunch of sluggish traffic, also included some in town traffic and about 7 minutes of idling to keep the truck cool while the Mrs. ran into a store to pick up some things. I know if I can keep the truck under 60 MPH I can pretty easily hit 20 MPG if the grade is fairly flat. Have even pushed 22.5 MPG on secondary roads at 45-50 MPH without many stops or traffic.

I even run 9 quarts of oil in the crankcase, wait for it ........... all the experts will chime in how the engine crankshaft is hitting the extra oil and causing it to foam up and will cause imminent engine failure, I do not know how to check oil and so many other negative things. Funny how things are just find, no oil leaks, no oil consumption, no problems. Newsflash, all I did was match the oil level that the engine shipped with from the factory. Quite a few open minded people have found the same to be true and are also running 9 quarts during an oil change. This makes the engine dipstick read just slightly above the top hash mark, right where the engine oil was at time of delivery. Have seen the same thing in the 2025 models as well.

I also have a Range Auto Stop/Start and DFM bypass installed on the truck since around 275 miles. I can go in and search and see what the lifetime fuel economy has been on the truck in the ECM with one of my more advanced scan tools and I have around 17.8 MPG lifetime mileage with all in town driving, waiting at stop signs and stop lights, in stop and go traffic and in drive thru lines. So I see nothing wrong with the 0W40 impacting fuel economy and add to this I have the Range Auto Stop/Start and DFM bypass so people would think I should be getting 5 MPG lower fuel economy than advertised. Its mouse nuts different, cannot see people claiming 0W40 is causing enough of a change in performance ofrMPG to even notice.

Hell, I have even installed the NextGen valve body upgrade kit and an aftermarket trans pan that holds 2 1/2 quarts more trans fluid. The NextGen kit boost the transmission line pressure slightly so this probably has slightly negative effect on fuel economy, however, the NextGet transmission valve body upgrade kit makes the truck shift so much better, like it should have from day one.

If you really have something going on, this probably means your engine may be on the way out??

 

[Doubeleive]

Hello All,

Just visited my local dealership and had my 22 XL checked for the recall and ended up with the new heavier weight oil and extended warranty.

I couldn't be more disappointed with the performance of the engine as it now feels sluggish to accelerate, fuel economy has dropped roughly 30% and there is no way this baby is still outputting 420 BHP on the 6.2L

Yes, I know the heavier weight oil creates more drag/friction on the motor. But the difference is noticeable and unacceptable IMO.

Anyone else get the oil change and experiencing this issue?

your either coo-coo crazy or something else is wrong with it
if anyone was going to feel the difference in engine performance from a very tiny change in oil viscosity it would be me and there aint no way
we are talking 0.1% to 1.5% difference at the most
so unless you are doing track runs from 0-140 on a digital timer (using comparing viscosity's), you will not feel or notice any difference
on a 60 second track run that calculates to less than 1/10th of a second

 

[2024 White Tahoe]

Hello All,

Just visited my local dealership and had my 22 XL checked for the recall and ended up with the new heavier weight oil and extended warranty.

I couldn't be more disappointed with the performance of the engine as it now feels sluggish to accelerate, fuel economy has dropped roughly 30% and there is no way this baby is still outputting 420 BHP on the 6.2L

Yes, I know the heavier weight oil creates more drag/friction on the motor. But the difference is noticeable and unacceptable IMO.

Anyone else get the oil change and experiencing this issue?

What are your pre and post fuel economy figures? Under what driving conditions? Premium fuel only?

 

[Vinnoto1]

Either you have an issue, or it is in your head.

I have had 0W40 in my 6.2 since I passed the inspection mid June.

I reset the Trip 2 trip odometer at that time, I am averaging exactly the same MPG over the past 2000 miles as I averaged over the initial 38000 miles (I had never reset Trip 2).
Otherwise, my ride is all the same as it always was.

Now, that said, could the dealer have bungled something up, possibly, but would think a Check Engine Light would be on if something like a spark plug wire was removed, etc....Got any Buddies with a Yukon, go drag race them.

Recall, your engine is naturally aspirated. When the temps go up, and the humidity goes up, there is a performance loss; same thing happens in boating, to the point where some people i know have a different pitch prop for cool weather vs hot. 30% loss in fuel economy not so likely though.

Appreciate the response, it probably is all in my head lol. I am forgetting it’s 100 degrees out and humid right now with the ac blasting isn’t helping my case. Guess i just need some more time behind the wheel to get used to it.

 

[Vinnoto1]

What are your pre and post fuel economy figures? Under what driving conditions? Premium fuel only?

Always premium fuel 93 octane. To be honest I don’t have that large a data set to work with yet as it was very recent but I was averaging 15/18 and it’s been roughly down to 10/12.

 

[Vinnoto1]

I have not had 0W20 engine oil in my truck since 544 miles and my truck is a 2025 with a July 15, 2024 engine build date so it is not within the recall window. I currently have 9,000 miles on the truck. Just took a 350 mile trip the other day in 105F weather and ended up with 18.5 MPG driving the truck hard, 80+ at times and having to pass a bunch of sluggish traffic, also included some in town traffic and about 7 minutes of idling to keep the truck cool while the Mrs. ran into a store to pick up some things. I know if I can keep the truck under 60 MPH I can pretty easily hit 20 MPG if the grade is fairly flat. Have even pushed 22.5 MPG on secondary roads at 45-50 MPH without many stops or traffic.

I even run 9 quarts of oil in the crankcase, wait for it ........... all the experts will chime in how the engine crankshaft is hitting the extra oil and causing it to foam up and will cause imminent engine failure, I do not know how to check oil and so many other negative things. Funny how things are just find, no oil leaks, no oil consumption, no problems. Newsflash, all I did was match the oil level that the engine shipped with from the factory. Quite a few open minded people have found the same to be true and are also running 9 quarts during an oil change. This makes the engine dipstick read just slightly above the top hash mark, right where the engine oil was at time of delivery. Have seen the same thing in the 2025 models as well.

I also have a Range Auto Stop/Start and DFM bypass installed on the truck since around 275 miles. I can go in and search and see what the lifetime fuel economy has been on the truck in the ECM with one of my more advanced scan tools and I have around 17.8 MPG lifetime mileage with all in town driving, waiting at stop signs and stop lights, in stop and go traffic and in drive thru lines. So I see nothing wrong with the 0W40 impacting fuel economy and add to this I have the Range Auto Stop/Start and DFM bypass so people would think I should be getting 5 MPG lower fuel economy than advertised. Its mouse nuts different, cannot see people claiming 0W40 is causing enough of a change in performance ofrMPG to even notice.

Hell, I have even installed the NextGen valve body upgrade kit and an aftermarket trans pan that holds 2 1/2 quarts more trans fluid. The NextGen kit boost the transmission line pressure slightly so this probably has slightly negative effect on fuel economy, however, the NextGet transmission valve body upgrade kit makes the truck shift so much better, like it should have from day one.

If you really have something going on, this probably means your engine may be on the way out??

Thank you for the response, similar driver here. I chose the 6.2 for a reason and enjoy driving it aggressively at times. it just struck me to notice ina short period of time the economy dropping so low and feeling sluggish. Albeit, the weather and me being my own worst enemy expecting to fly all the time doesn’t help. Will def keep an eye on it for the near future.
The range unit your using is it the one the plugs in behind the wheel well or under the dash? I’ve hesitated to get one but honestly hate those features.

 

[Vinnoto1]

Either you have an issue, or it is in your head.

I have had 0W40 in my 6.2 since I passed the inspection mid June.

I reset the Trip 2 trip odometer at that time, I am averaging exactly the same MPG over the past 2000 miles as I averaged over the initial 38000 miles (I had never reset Trip 2).
Otherwise, my ride is all the same as it always was.

Now, that said, could the dealer have bungled something up, possibly, but would think a Check Engine Light would be on if something like a spark plug wire was removed, etc....Got any Buddies with a Yukon, go drag race them.

Recall, your engine is naturally aspirated. When the temps go up, and the humidity goes up, there is a performance loss; same thing happens in boating, to the point where some people i know have a different pitch prop for cool weather vs hot. 30% loss in fuel economy not so likely though.

Wifey does have 21 short with a 6.2 but i’m not even gonna ask that question lol.

 

[West 1]

Heat and humidity can affect your power level for sure. I agree with others, you should not feel the oil change at all. Maybe they tuned your engine while it was in the dealer?

 

[Kpwweb]

How long was your truck in the shop? Could be the dealer reset the ecm somehow so the truck is relearning fuel trims? I always get really poor fuel economy when the truck is relearning fuel trims.

Also, I think chevy overcooks the fuel curves when either cold or warm. I get the best fuel exonomy at 70-75F. Terrible either side of those temperatures.

 

[jfoj]

Thank you for the response, similar driver here. I chose the 6.2 for a reason and enjoy driving it aggressively at times. it just struck me to notice ina short period of time the economy dropping so low and feeling sluggish. Albeit, the weather and me being my own worst enemy expecting to fly all the time doesn’t help. Will def keep an eye on it for the near future.
The range unit your using is it the one the plugs in behind the wheel well or under the dash? I’ve hesitated to get one but honestly hate those features.

The Range ASS/DFM bypass module plugs into the ECM behind the drivers side wheel liner. Highly suggest getting one of these, no regrets what so ever.

One thing GM did with these trucks is they screwed up the ignition timing mapping. When tipping into the throttle in a gear other than 1st, you will feel the "fish biting at the bait" as the ignition timing maps are jumping around and the ECM retards the ignition by over 30 degrees, this causes the "fish biting at the bait" feeling and really causes a loss of power down at the lower RPM's.

BMW did this many years back as well and if you got the timing pulled you could be full throttle in 2nd-4th gear and the vehicle felt like an anemic 4 cylinder. Often had to go to aftermarket tunes to get around this problem.

Seen this before on many vehicles and I have the data that shows what is happening.

 

[Vinnoto1]

How long was your truck in the shop? Could be the dealer reset the ecm somehow so the truck is relearning fuel trims? I always get really poor fuel economy when the truck is relearning fuel trims.

Also, I think chevy overcooks the fuel curves when either cold or warm. I get the best fuel exonomy at 70-75F. Terrible either side of those temperatures.

Only a few hours but multiple items were reset like seat position and other memory features so likely they did do an update.

 

[2024 White Tahoe]

The Range ASS/DFM bypass module plugs into the ECM behind the drivers side wheel liner. Highly suggest getting one of these, no regrets what so ever.

One thing GM did with these trucks is they screwed up the ignition timing mapping. When tipping into the throttle in a gear other than 1st, you will feel the "fish biting at the bait" as the ignition timing maps are jumping around and the ECM retards the ignition by over 30 degrees, this causes the "fish biting at the bait" feeling and really causes a loss of power down at the lower RPM's.

BMW did this many years back as well and if you got the timing pulled you could be full throttle in 2nd-4th gear and the vehicle felt like an anemic 4 cylinder. Often had to go to aftermarket tunes to get around this problem.

Seen this before on many vehicles and I have the data that shows what is happening.

I have a 2024 Tahoe Premier 4WD and have noticed the effect that you described while driving in RWD.

To me, it feels as though the rear wheels are slightly slipping on road contamination, although they are not.

It is an annoying feeling and makes me feel that there is something wrong with my vehicle.

 

[Doubeleive]

Only a few hours but multiple items were reset like seat position and other memory features so likely they did do an update.

I can only guess that any updates have something to do with how P0016 is set, I wouldn't put it past gm to tweak it a little

 

[jfoj]

I have a 2024 Tahoe Premier 4WD and have noticed the effect that you described while driving in RWD.

To me, it feels as though the rear wheels are slightly slipping on road contamination, although they are not.

It is an annoying feeling and makes me feel that there is something wrong with my vehicle.

Example of timing being retarded when engine load is increased.

Not a good example of the fish biting, but gives you an idea as to what the ignition timing is doing. 30 degrees of retards is a HUGE drop in power.

 

[2024 White Tahoe]

Example of timing being retarded when engine load is increased.

Not a good example of the fish biting, but gives you an idea as to what the ignition timing is doing. 30 degrees of retards is a HUGE drop in power.

View attachment 463909

The feeling definitely makes me feels as if something is wrong. Sort of feels like making a slow turn and the rear end chattering (although I am driving straight and not accelerating rapidly).

 

[jfoj]

Pretty much what you are feeling, you should not feel this in 1st gear, but if you tip into the throttle fairly aggressively in 2-4th or maybe even 5th gear you will feel this "nibbling", as long as the transmission does not downshift. If the transmission downshifts and the RPM's go up above say 3000-3500 then maybe you will not feel the "nibbling". Bad engineering and programming.

 

[NELLY1947]

Hello All,

Just visited my local dealership and had my 22 XL checked for the recall and ended up with the new heavier weight oil and extended warranty.

I couldn't be more disappointed with the performance of the engine as it now feels sluggish to accelerate, fuel economy has dropped roughly 30% and there is no way this baby is still outputting 420 BHP on the 6.2L

Yes, I know the heavier weight oil creates more drag/friction on the motor. But the difference is noticeable and unacceptable IMO.

Anyone else get the oil change and experiencing this issue?

I did the oil (upgrade) change myself to the 0-40 mobile 1. I asked my dealer and seeing as my number was not in Q yet they agreed with me to do it. And they would owe me an oil change.
BUT here is the kicker... I had the shop take a sample of the oil and give me the used oil filter and I sent them to be tested. The facility told me there may be no shavings or particles in the filter as this is my 5th change in aprox 15000 miles. (I'm nuts for changing oil and filters.) WAIT HERE IT COMES.... there was 4.1% fuel in the oil. I actually commented the oil looked like water at the shop. When the testing facility saw this they called me and asked if this was a GMC 6.2? I asked why? And was explained they have seen this in others. When I confirmed I do not use the traffic light start stop and also always run the truck once started. I was told to contact the dealer ASAP. I did that and was told it could be normal. IMO that is BS. So the next oil change will also be tested.
Can you tell me what mileage / time they gave on the warranty. Too bad in Canada we don't have lemon laws.
As for the mileage can't tell but I will agree that in order to get it to "move" I have to put it in sport mode and that helps. But kills the mileage .
I wish someone could tell me how to force them to take the truck back..

 

[RANDY S]

Hello All,

Just visited my local dealership and had my 22 XL checked for the recall and ended up with the new heavier weight oil and extended warranty.

I couldn't be more disappointed with the performance of the engine as it now feels sluggish to accelerate, fuel economy has dropped roughly 30% and there is no way this baby is still outputting 420 BHP on the 6.2L

Yes, I know the heavier weight oil creates more drag/friction on the motor. But the difference is noticeable and unacceptable IMO.

Anyone else get the oil change and experiencing this issue?

I have not noticed the performance issues mentioned but am upset that the dealer said that oil changes in the future will be much more expensive because of the 40wt oil. GM should address this with their customers.