2nd Gen Non-Engine/Transmission Rear diff fluid

[DLausche]

I've read many posts about rear diff fluid, but couldn't find the answer...



The manual indicates sae 90 weight gear lube in the rear diff and I've read about many having good luck with 75W-140 synthetic. Well, I happen to have plenty of 85W-140 GL-5 gear lube already on hand, but it is not synthetic or blended. Would this be suitable in the rear diff or not? I was thinking about using this 85W-140 plus 4 oz of friction modifier in my next fluid change. My truck is mostly a daily commuter, but we do tow a 30', 7000 lb travel tailer a dozen or so times in the summer. Am I crazy for even thinking about using the 85W-140?



-Deon

 

[EricBu12]

I would say that would be good for the summer and towing. . I don't know about your winters there though.



I have the Amsoil 75W/90 Synthetic. I just changed it from the LE 90wt.

Generaly, a multi wt, is better for winter and the synthetic helps for keeping the slipperyness on the gears... .

 

[TBarrett]

Chart help

Did you know the dealer can run a list of your truck as it came with everything on it and then you can cross the #'s with another chart they have to tell you exactly what fluids your truck has. Cool. All they need is the serial # in the computer perferrably get from where you bought the truck.

 

[DLausche]

Thanks for the feedback. I think I will use this 85W-140 for the rest of the summer and then switch to a synthetic for the cold winter months.



-Deon

 

[Royal]

If you check your owners manual under the towing/heavy duty section you will find that it says to use 85-140 Wt. lube in rear axel.

 

[Elite1]

My manual (96') it says if you plan on towing anything heavy, you should change to synthetics in the rear end. I have Mobil1 synthetic, forget the weight, but it's the only one they make.