I've upgraded to a 5th wheel and now am towing just above 10,000lbs. Should I change the rearend fluid to the 80-140w now. Is it fine to run year round or are you better to use it in towing season. Any info is welcome as a search brought no info.

Thanks:)
mark

I am towing 10K pound 5th and using the 75W-90 GM Synthetic fluid all year round. 37,000 miles and no problem. I put on about 5k a year towing.