6.2L towing

[Bowzer]

Hello all!
I just purchased a 22 TB 6.2L. Today I pulled my quad trailer which is a 14’ aluminum with my sxs loaded on and is extremely easy to pull. I know my gearing is low I believe it is 3.2 but will get a definite answer tomorrow. While on the highway doing 103 it would not go into 10th at all and was revving at 2500 the entire time and my fuel mileage went from 13L/100kms to 29. I pulled this same trailer with my 2019 TB 5.3L and was getting 21L/100kms I can’t remember gearing but I remember it mainly ran at around 1500 RPM. I previously owned a 2022 gmc AT4 with the 6.2L again I can’t remember gearing but pulling the same trailer I was averaging 17-19L/100kms. Is it possible that my 2 previous trucks were geared that much higher and my current truck being a lower ratio of 3.2 that my truck will always pull like this and run at a higher RPM all the time or could it be something wrong with my truck. I have 2700kms on my truck and my trailer is 500lbs and my sxs is 1800 lbs.
Thanks in advance for any input.

 

[PennStateLarry]

Wonder if this has something to do with the transmission service bulletin that was put out by GM.

 

[Bowzer]

I have no idea
I contacted my dealership and I have my truck booked in and they want me to bring my trailer.
Will post with the diagnosis

 

[JBJ]

Wonder if this has something to do with the transmission service bulletin that was put out by GM.

Do you have link to bulletin or # ?

 

[PennStateLarry]

Do you have link to bulletin or # ?

GM Service Update number: N222383250
I read the article on GM Authority web site.

 

[Bowzer]

And of course they tell me theirs nothing wrong with my truck. Even on the highway it won’t go into 10th unless I slowly drop my speed to 96kms/hr then it will shift to 10th
My 22 at4 with same motor tranny and gear ratio acted completely different from my new truck on the highway I averaged 10.5L/100kms and my new truck best I’ve seen is 13.5 and I know I need to let it break in before I can start watching fuel mileage but this truck is even showing it’s not in 10th just by the difference in RPM…. But everything aside fkn love this truck love the 6.2