RichP9

So ive decided that im going to change the fluid in the rear diff of my truck, it has 125k on it, i dont know if or when its ever been changed, plus its started to have a little shudder when i take off while turning, so i figured its time for a change. whats everyones opinion on the gear oil with the additive already in it, opposed to putting plain gear oil in it plus the additive, is their an advantage to either?
no oil brand wars please.. thanks guys!

grss429

Add your own LSD additive. the oils doesn't actually have all that much of LSD additive

HeathMc

I used royal purple and didn't have to add any. No shudder. But I think most people add it just to be safe.

Toshbar

I used valvoline synthetic 80-140 or whatever it calls for(front is different weight), which said not to add LSD FM. Got the shudders turning and added 1.5 bottles (6oz.) of FM. Been great since. I jacked up the drivers side of my truck to add the additional 6oz of fluid without cracking the cover to drain some gear oil out.

dnlow

I also used the Valvoline synthetic but had to add a 4 oz bottle of additive later.

Briby37

Agree 100%, I use valvoline and then add LSD additive. Have done this in a handful of cars/trucks, never had any issues.

scobar

iTrader: (4)

Also if its a traclok put in new clutches and soak them in friction modifier prior to reassembly. The best additive IMO is the ford stuff.

ColdinCanada

Forget the diff fluid, just pour in friction modifier until she's full.

DISCLAIMER:

The statement above was, for all intents and purposes, an attempt at humour. Under no circumstance should the statements made by this author be taken as advice or anything remotely relating to a real world situation. Should you choose to take this as genuine mechanical direction you are proceeding at your own risk and the author will not be found liable.
All rights reserved-ColdinCanada 2015

RichP9

i wanted to use mobil1 in it but i couldnt find it anywhere local without the modifier in it already but i picked up a bottle of the modifier at ford, and they said to use a half bottle if the oil already had it in it, so ill give that a shot and add the rest if need be. i havent changed it yet but ill report back

techrep

iTrader: (1)

I used Mobil one and added a bottle of FM...good to go !