Differential oil change

[gdblake]

What brand fluid is recommended for the 500+ mile fluid change. Are there any commonly available brands that don't have to be ordered like Red Line or Amzoil? Do friction modifiers have to be added to the ltd. slip axle< I know they have to be added for Ford's rear end. Thank You

[Turbo Al]

gdblake:
IF you were towing at or near capacity a good deal of the time I would stick with the Expensive GM stuff. I tow maybe 5,000 miles a year (7,000 lb tow & cargo) and I use Castrol Syntec. No additive are needed in the locker rear diff.

[gdblake]

Thanks Turbo Al, I'll probably tow 5000 miles in August, and that's probably most of the towing for the year. Do you know what the part number of the GM fluid is? Do I need to change the fluid, early, as many have posted. Thanks

[LanduytG]

Their is no need to stick with the GM grape juice when heavy towing. The GM stuff is nothing special at all. Any GOOD synthetic gear lube can be used. Not sure about other synthetics but the Amsoil Series 2000 does not requir limited slip additive.

Greg

[Turbo Al]

LandytG is correct but for the warrenty period I would run the GM stff just because sometimes Dealers attempt to give you a lot of grief over any little thing. When the rearend in my Jimmy blew, the Service Manager said it would NOT be covered because I was towing more than what GM spec'd -- trailer was still behind the truck when I brought it in. I just plain "LOST" it and told the dirtball to go out and read the trailer weight off the spec plate because in fact it was 2,500 lbs BELOW the GM spec. Then I got a call right from GM service or should I say DIService with some WILD claim that I was doing Netural drops (put in Netural and reving it up and dropping it in gear) to blow the rear end. It took over a month to get this mess straighted out & it ruined the whole Hunting Season.

gdblake: I would change out the fluid at 500 miles & then again after 500 miles of towing. I actually changed mine after 800 miles of towing -- when I got to my Hunting spot -- It only takes 15 mins. The first change at 500 I would use any good quality oil the second (after 500 miles of towing) I would put the GM stuff in if you are towing at/near capacity. I don't have a part number -- I don't use the GM stuff because I tow/haul 7,000 lbs tops at this point.

[gdblake]

Thank you, again--LanduytG, and Turbo Al.