GTVAPSAMTIK

Hi guyz I just went and bought mobile 1 / RV. It cost me roughly $41 for 2x bottles of mobile 1 and RTV. I have never changed the differential fluids before.

I just wanted to get your openion if this is everything I need before I open the differential on my 2001 Mustang GT ?

Z28KLR

Should be good to go. I didn't know until recently, but I guess synthetic fluid negates the use of the friction modifier, so looks like you have everything. I thought the diff took slightly over 2qt. to fill, but it's been a while since I did mine so I could be wrong. The only thing I see missing from your picture is a 12"-18" piece of rubber hose to hook on to the end of the bottle and run into the filler plug hole. Have fun.

Timspony

...Do you need the MC friction modifer with the Mobil 1?

03BottleFedGT

yes you have to run friction modifier with mobil 1. i belive royal purple is the only one you dont.

Timspony

That's what I thought....

01MGGT

I was pretty sure people were saying mobil1 you don't need fm because it's got it for lsd's already plus that in the pics is 75-140 weight and I could have sworn it calls for 75w90 but I honestly don't remember

Black_GT_02

I used Mobil 1 and friction modifier. Haven't had a problem yet.

I read some things about how Royal Purple incorporating the FM in theirs wasn't nearly up to par as going Mobil 1 + FM.

03BottleFedGT

they take 75-140

WannaBeGearHead

Wow! I searched this topic and there is a lot of different answers. There seems to be a general consensus that running RP you don't need FM.

Read this thread. I think Cliffy answers what weight oil a 2001+ takes.
https://mustangforums.com/forum/4-6-...-how-much.html

For those who don't want to look, the Ford manual clearly states 75w140 for 2001 1/2+ Mustang rearends.

teej281

nevermind...found my answer.