Hey All:
i just installed a new/used Posi rear end in my 95 1500 Ram 4x4. Before I did, I removed the cover, drained the old fluid & put in new 90 wt. gear lube, I hear I need to add an additive??? Is it REALLY needed?
Thanks
b

 

i also had this question b/c i didnt get the additive, and did it. but it runs fine as a whitsle.

 

It may run fine for a while but if you have the posi trac/anti spin (some people call it diff. names) you need the additive because there are clutches in the rear and the additive for them to work right. It might seem fine for now but after a while it won't be.

 

What kind of gear lube did you put in? Some already have friction modifier additives. Check the bottle. Amsoil and Mobil1 both have it.

If it doesn't, then yes you need to go get some and put it in. If you don't, your limited slip won't function correctly and you will have wasted your time doing all of this.

 

if you dont add it in it can slowly wear down your clutchpacks faster than normal... i learned this the hard way... well the stealership did... there cost!!!!!!! boneheads...

 

well i bought castrol fully synthetic gear lube 75w90. so do i need the additive or not?anyone know if it already has it in it......please help, i will cry if my truck is hurtin on the inside, lol.

 

You only need the additive if you have the optional limited slip differential. If you have the standard open differential, it doesn't matter. And like I said in my post above, check the bottle. It will say on there if it already contains the additive.

 

i just swapped diff fluids in 2 of the 3 trucks we have and used the Red Line 75W90 gear oil, it states right on the bottle that it has the additive in it. check the bottle, if it doesnt state that it has it, then go get some and add it.