Engine/Transmission (1998.5 - 2002) 75W-140 synthetic for LSD

[Mabrown]

The owners manual recommends SAE 75W-140 synthetic for the rear differential for towing. I have the limited slip rear end and changed mine to AMSOIL 75-140 and added limited slip lubricant. I don't remember if it did it before but now when it is cold I feel the rear end kind of shudder for the first few corners of the day. Does anyone else run the heavier synthetic in their LSD and do you notice any difference than with the factory lube?

 

[C Schomer]

No LSD noises with the OEM 75w90 but it was black and very stinky at 9k. Then Ams 2k 75w90 and had to use the additive. Also developed ring and pinion noise with the Ams after 13k miles. Then RP 75w90 syn. Ring gear noises eventually went away and didn't need the additive. Then RP 75w140 syn - didn't need additive at first but after about 5k miles, I need to get some. Craig

 

[tarussell]

I changed to synthetic's( Valvoline ) and did not add the LSD additive when my truck had 532 miles on it. It shudders and moans the first few turns every time it sits a while. I feel like the clucthes don't get enough oil between them until the diff. slips the clutches a little. It will also constantly chirp the tires on a sharp turn. I did not want to add the LSD additive because it promotes clutch slippage for better road manners. I just live with the tire chirping on road for better traction off-road.



If the creeking and moaning bothers you I would add another does of LSD additive and take the truck to a big open parking lot and do some figure eights to work the additive into the clutches.



Just my $. 02

 

[klenger]

Did you turn a few figure 8's (both directions) after adding the fluid? I put in Amsoil 75w-140 in mine and didn't need any modifier.

 

[John Berger]

You definitely need to do the figure 8's after changing the lube. The Amsoil lubes do not require friction modifiers to be added. I've changed the gear lube three times in 78K miles and never added the friction modifier.

 

[Phil Stuart]

Gear Lube

After I put on the Mag Hytec and filled with Amsoil 75w 140 I drove to a good open parking lot by the Food Lion where I live and did the figure eight thing about 8-10 times. Some guy comes out and is looking at me like I'm crazy or something,Oh well I did not need the modifier at all (yet anyway).



Phil