What type gear lubricant?

[AWay]

This question is not so much what brand, I know we are all divided over Mopar, Amsoil, Royal Purple, etc. They all have their qualities and it's an age old debate about which is best, if one is. My question to you is for the rear differential have you stayed with 75w90 or went to 75w140. If so, do you think the 75w140 helps for towing. When I tow it's a 15,000 lb 5th wheel.



Getting ready to install my PML diff cover and would really appreciate some input as to which weight lub to put back in. Thanks to all in advance.

 

[Bob Wagner]

just installed my mag cover and used mopar 75-140 and its suppose to be great for towing .

 

[CHolman]

I have R/P 75-140 in mine. I wished I had the mag cover, but I keep finding go fast goodies and pass it up. No problems with the 75-140 in mine.

 

[klenger]

According to all the info I've read, 75W90 100% syn is the only fluid approved for the AAM axles. I use Mobil 1.

 

[DPKetchum]

75w90 Amsoil severe gear for me. My truck is hooked to 10k 99% of thetime.

 

[rbattelle]

Check this out. Very interesting.



Ryan

 

[DieselFiend]

I'm thinking, go with what the book says. If it said, 75-140 was ok then I'd use it but it doesn't. It calls specifically for 75-90. I changed mine with royal purple. It's working out just fine and I also tow.

 

[Dieselnerd]

75W-90 Mobil 1 in mine. I also follow the book. It didn't say to use the 75-140 for towing like my second gen manual did. My gears looked really good at the first change. No big wear particles, nice smooth gear contact wear.