just change rear end grease put in 75w90, then saw post about using i think it was 90w 140 for heavy towing. i tow a 9000 lb enclosed car trailer in the summer. its not a 5th wheel. should i change this to the heavier graese in the spring?

 

Personally, I would just change to the 75-140 when it comes time for the next scheduled change...

 

I would say towing at or over 23,000lbs truck and trailer combined.

 

Whats heavy towing ?? For your 2500 truck it will be at max or above max capacities which they are designed to operate at. I tow a 11200 lb 5er and have ran 75w-140 Redline synthetic since the first fluid change at 18k.
JIM

 

Maybe look at it this way. The oil costs the same, the change is the same. It surly does not hurt the rear to run lighter with the heavy duty oil. So put the heavy synthytic in it and forget it.

 

i would classify heavy towing something like a load that is heavier than 20k lbs or so. anything less is just normal driving

 

i just change the the lube so next change will be awhile will it hurt to run it that long or should i just bite the bullett and change it in the spring before i start to tow?

 

No more than you are pulling, I would not worry about it. That is only my opinion though. You should have synthetic in it in any case.

 

It comes with 75-w90 synthetic, and lots of people tow quite a bit before the 1st fluid change with no damage.

As long as the 75-90 you put in meets specs (GL5 synthetic), I'll stick with my earlier comment in that if it were mine I'd wait to change to 75-140 at the next scheduled change.

 

I tried the 75-140 (full synthetic, national brand) and had terrible grinding when turning corners in the wife's truck. Changed back to Mobile 1 75-90 (same brand) and have had no more noise.
Reminded me of the noise the Dana in my truck makes when you don't get enough of the friction modifier in it.
The service requirements listed in the owners manual for the '03 state 75-90, so as long as I meet all of the other requriements (syn, GL-5, etc.) I know that I am within warranty parameters.

I define heavy towing as 80% of rated GCVWR.

Dry Creek

 

i put royal purple in it seems fine but have not towed with it . i mite hook up to trailer and take a spin in my spare time. thanks for the input !