Planning on changing my rear diff fluid this week before winter time and to make sure everything lasts as long as it can seeing i have the supposedly unreliable 9.25 with LSD. So my question is i've been reading that i should use 75-140 full synthetic with the mopar LSD modifier stuff in the 9.25 with LSD. Am i safe to use the 140 or does it use 80-90..just wanna know what i should pick up on my way home friday and if i can i wanna use the 140 to be on the safe side and keep it running cooler. Thanks for any help.

 

All the literature I have states 75w90 for the 9.25
Some say to bump up to the 140 if you'll be towing. I haven't found anything in writing, except on forums, to back that up tho'.
I changed mine for M1 75w90, and whatever brand that Advance sells for the LSD modifier.
One thing I have read (and practiced) in shop/service manuals, is right after the change, take the vehicle out, to like a parking lot, and do several 'figure 8s' to get the new stuff properly worked into the gears.

 

yea i also read about the figure 8's or whatever to pump it thru...i think i'm gonna go with 75-140 just to keep it cooler since i make a lot of long trips to school and tend to drive it pretty hard during the summer but i'd like to hear somemore opinions tho. on a different subject DANBLK did you happen to change the tranny fluid in your truck? if you did what fluid did you put in it or did you get the mopar stuff and how hard was it. my mechanic that i trust 100% said mines find but i'd still like to change it out just to know its done.

 

sorry answering my own post again anyways i thought of another question...im thinking im gonna go with mobil one or royal purple or one of the ones with friction modifier already in it but can i add a little bottle of it anyways just to make sure it has enough or would that damage it?

 

Yep, changed out the tranny oil too. Simple job.

I used this:



And one of these:



And you'll need a 17mm hex wrench for drain/fill plugs.

I've read that the syn. gear oils that saythey already have a component for the LSD,are not 'harmed' in any way by adding the modifier of your choice, nor is the diff. in danger with this practice. BTW, according to the manuals, the 9.5 LSD requires 4ozs of additive.

Good luck. Let us know what you use, and how it turns out.

 

sounds good...one more question did you notice any smoother shifting or reduced effort or anything when you did the tranny fluid? thanks again

 

LOL, tranny still clunky as ever! I just feel better knowing that fresh oil is in there.

 

alright think i finally made up my mind on gear oil. after a bunch of going back and forth im going to put in mobil 1 synthetic 75w-90 with 4 oz of friction modifier just to be on the safe side. i figure since its going to be cold for the next 5-6 months i dont need the heavier weight and i use mobil one in the engine so might as well keep in the same in the rear. now hopefully i dont find a little surprise for me when i take off the cover...wish me luck lol.

edit: do i need any special thing to fill the diff back up or is it easy enough to just pour it in the filler hole till its full with at least 2.32L?