Which diff fluid.

[HwyKng]

Ive searched online and really havent come up with any helpful information. My car has 26k and i want to change out the rear diff fluid. My ? is which fluid other than OEM stuff is everyone using? I have Royal Purple in the transmission and was thinking about putting the same in the rear. What weight is needed and any additives are you guys & gals using?
Thanks

 

[keith89]

Ive searched online and really havent come up with any helpful information. My car has 26k and i want to change out the rear diff fluid. My ? is which fluid other than OEM stuff is everyone using? I have Royal Purple in the transmission and was thinking about putting the same in the rear. What weight is needed and any additives are you guys & gals using?
Thanks

op:

 

[stangliter04]

TTT will it be okay to run 75W 90?

 

[HwyKng]

30 views and no help. cmon guys

 

[mu22stang]

75W140 with friction modifier. I'd advise against Royal Purple if you are worried about geat whine. My rearend is stock and switching to RP gave me a nasty howl. I'll go AMSOIL next round. If you go RP, no need for friction modifier.

 

[Jomo1994z71]

On the same subject...I hear, if you go with RP 75w-140 it already has friction modifier in it, so you don't have to add it. Is this correct?

 

[DocB]

Amsoil Severe Gear 75W-140 also has the friction modifier in it according to Amsoil. But, if you experience chatter, a little more FM should be added.

 

[mu22stang]

On the same subject...I hear, if you go with RP 75w-140 it already has friction modifier in it, so you don't have to add it. Is this correct?

...If you go RP, no need for friction modifier.

That is true. It's integrated into the RP formula, FWIW. I'm not a fan and wish I hadn't even changed it from factory oil.

Amsoil Severe Gear 75W-140 also has the friction modifier in it according to Amsoil. But, if you experience chatter, a little more FM should be added.

Didn't know this.

 

[HwyKng]

Amsoil Severe Gear 75W-140 also has the friction modifier in it according to Amsoil. But, if you experience chatter, a little more FM should be added.

well dammit, still confused on what to run. :shrug:

 

[mu22stang]

At 26K miles, I wouldn't be in a hurry to change it. Unless you're running open track events and really heating up the differential, you're probably fine for another 30K miles or more.

 

[JB]

At 26K miles, I wouldn't be in a hurry to change it. Unless you're running open track events and really heating up the differential, you're probably fine for another 30K miles or more.

I believe this is the first time I've ever had an alternate view of something you posted, but here goes:

Unless OP knows that fluid was changed at least once in its life, he should change it now.

You always want to get the break-in material out of there.


I found a link, cuz I'm getting tired of typing today

:read: Change Gear Lube After Break-In Period for Long Differential Life

 

[skaarew04SVT]

i use RP 75W140 with no friction modifier. its already in there

 

[mu22stang]

I believe this is the first time I've ever had an alternate view of something you posted, but here goes:

Unless OP knows that fluid was changed at least once in its life, he should change it now.

You always want to get the break-in material out of there.


I found a link, cuz I'm getting tired of typing today

:read: Change Gear Lube After Break-In Period for Long Differential Life

I'm still uttely confused as to why my differential howls like there's no tomorrow after my 32,XXX mile fluid change when it was silent before. I guess I was just playing devil's advocate. Interesting article, thanks for the link JB. :thumbsup:

 

[TuFFstang]

gear oil

I went Mobil1 75/140 LS, 1.3L (limited slip) + 4oz Friction Modifier. Found out Mobil1 has a FM integrated, BUT you can add Manufacturer's recommend amount for correct applications. So for me that means add it.

 

[BlackBeauty44]

RP in my rear 75w 140. This is my third mustang that i have switched gear oil and went with RP with zero problems. Just go with it. Mu22stang are you sure your bearing are ok??

 

[mu22stang]

RP in my rear 75w 140. This is my third mustang that i have switched gear oil and went with RP with zero problems. Just go with it. Mu22stang are you sure your bearing are ok??

Nope. What's a quick check for the hub and inner?

 

[BlackBeauty44]

inner and outer hub bearings??

 

[mu22stang]

No, hub bearing and inner/differential bearings. I did the 6 o'clock-12 o'clock and 3 o'clock-9 o'clock test in the recent past as well as regularly torquing my hub nut to 250 lb-ft, so I think I think those are ok. But, how do you diagnose a differential bearing problem?

 

[cobracide]

Amsoil Severe Gear 75W-140 also has the friction modifier in it according to Amsoil. But, if you experience chatter, a little more FM should be added.

Just do this.

 

[HwyKng]

anyone know how much fluid to use?