What weight gear oil should I use?

[SteveD2]

I'm going to put some Amsoil gear oil in the rear diff of my Cherokee. My repair manual says "75W or 80W-90 for normal use" and "75W-140 synthetic for trailer towing". The reason I'm switching to Amsoil is for gas mileage, so I would like to use the thinnest I can get away with. Would it be ok to use 80W-90 for towing a <2000lb trailer? It says to use 75w-140 for trailer towing, but that is also up to 5000lbs. Also Amsoil is obviously better than the average dino 80w-90...

 

[Mitch]

I run Mobil 1 75-140 in my Jeep. The manual states the same thing yours does.

 

[sbc350gearhead]

I would run a good synthetic 75w90. I don't think that you will have problems with towing a trailer with a good synthetic.

 

[cousincletus]

I used Amsoil Series 2000 75W-90 oil in my '99 Cherokee diff and towed a 2000 lb. boat.

Never had a problem.

 

[SteveD2]

Alright...75W-90 it is.