Rear diff fluid?

Wich88 · April 18th, 2011, 08:51 AM

Wondering if you guys can figure this one out. So last week I had 3.73 gears, all new bearings and bushings, and new Moser axles installed with Royal Purple diff fluid. I picked the car up and when I took a turn I could hear the posi unit popping, sounded like something was binding?? Took it back to the shop and the guy said maybe it was the Royal Purple......I'm like WTF, lots of people use RP. So I changed the fluid Friday and I just put Valvoline back in with friction modifier.....and now the car is fine, no binding?? Doesn't make any sense.

LoveStangs88 · April 18th, 2011, 09:56 AM

Great... I got Royal Purple tranny fluid coming... I hope that crap aint as bad as their diff. fluid that you got.. So yeah what gives? RP is supposed to make things better not make em bind and snap crackle and pop! Maybe its just too new technology for our old 96's and our babys just need the good ol stuff? I'm not trying to steal your topic but does anyone else have good experiences with R.P tranny fluid and their differential fluid?

Wich88 · April 18th, 2011, 10:02 AM

Ha...the only thing that I can think of, is RP already has friction modifier in it. So maybe it was to much with the RP and the posi additive he put in.

JK7208 · April 18th, 2011, 11:36 AM

Originally Posted by Wich88

Wondering if you guys can figure this one out. So last week I had 3.73 gears, all new bearings and bushings, and new Moser axles installed with Royal Purple diff fluid. I picked the car up and when I took a turn I could hear the posi unit popping, sounded like something was binding?? Took it back to the shop and the guy said maybe it was the Royal Purple......I'm like WTF, lots of people use RP. So I changed the fluid Friday and I just put Valvoline back in with friction modifier.....and now the car is fine, no binding?? Doesn't make any sense.

I've read you still need to put the friction modifier in it even with the royal purple. I'm sure someone else will have more imput on it,

Wich88 · April 18th, 2011, 11:53 AM

That's what i thought. I did add it with the Royal Purple.

cstreu1026 · April 18th, 2011, 12:00 PM

I have run nothing but Royal Purple & a bottle of FoMoCo friction modifier in mine since I changed the gears in 2004 and have not had a single problem.

x7sage7x · April 18th, 2011, 12:00 PM

Adding friction modifier was a bad idea. With that said, what weight fluid did you use?

Wich88 · April 18th, 2011, 12:27 PM

The Royal Purple was 75w and the Valvoline was 80w. That's the only thing that I could think of, that I shouldn't have added the friction modifier with the RP. The car is fine now with the Valvoline. No binding anymore.

NatesGT · April 18th, 2011, 08:50 PM

I have a buddy that had a 240sx sr20 det motor in it. Pushing around 450hp to the wheels. The car ran great was a freakin beast. He put RP oil in at the next oil change, and within a week threw a rod. Thats the only experience ive been close to with RP.

April 18th, 2011, 08:51 AM	#1
Wich88 Regular 1997 SVT Cobra Join Date: Dec 2010 Location: GBT, Michigan Posts: 488 iTrader: 0 reviews	Rear diff fluid? Wondering if you guys can figure this one out. So last week I had 3.73 gears, all new bearings and bushings, and new Moser axles installed with Royal Purple diff fluid. I picked the car up and when I took a turn I could hear the posi unit popping, sounded like something was binding?? Took it back to the shop and the guy said maybe it was the Royal Purple......I'm like WTF, lots of people use RP. So I changed the fluid Friday and I just put Valvoline back in with friction modifier.....and now the car is fine, no binding?? Doesn't make any sense.

April 18th, 2011, 09:56 AM	#2
LoveStangs88 Regular 96 Mustang GT B There 1 Day. Join Date: Jun 2010 Location: Aurora, CO Posts: 460 iTrader: 0 reviews	Great... I got Royal Purple tranny fluid coming... I hope that crap aint as bad as their diff. fluid that you got.. So yeah what gives? RP is supposed to make things better not make em bind and snap crackle and pop! Maybe its just too new technology for our old 96's and our babys just need the good ol stuff? I'm not trying to steal your topic but does anyone else have good experiences with R.P tranny fluid and their differential fluid? __________________ PI Manifold. FRPP. Steeda. Magnaflow. BBK. Accufab. RAM. MGW. MSD. NGK. NTK. Billet. J&M. Powerslot. Hawk. Walbro. Motul. Fel-Pro. Dupli-color.

April 18th, 2011, 12:00 PM	#7
x7sage7x Regular 2001 GT Mustang Join Date: Mar 2011 Location: Ft. Huachuca, Az. Posts: 299 iTrader: 3 reviews	Adding friction modifier was a bad idea. With that said, what weight fluid did you use? __________________ 2001 GT Mustang Cheers!

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April 18th, 2011, 10:02 AM	#3
Wich88 Regular 1997 SVT Cobra Join Date: Dec 2010 Location: GBT, Michigan Posts: 488 iTrader: 0 reviews	Ha...the only thing that I can think of, is RP already has friction modifier in it. So maybe it was to much with the RP and the posi additive he put in.

April 18th, 2011, 11:53 AM	#5
Wich88 Regular 1997 SVT Cobra Join Date: Dec 2010 Location: GBT, Michigan Posts: 488 iTrader: 0 reviews	That's what i thought. I did add it with the Royal Purple.

April 18th, 2011, 12:00 PM	#6
cstreu1026 Regular All Motor 1998 GT Join Date: Mar 2011 Location: Xenia, OH Posts: 338 iTrader: 0 reviews	I have run nothing but Royal Purple & a bottle of FoMoCo friction modifier in mine since I changed the gears in 2004 and have not had a single problem.

April 18th, 2011, 12:27 PM	#8
Wich88 Regular 1997 SVT Cobra Join Date: Dec 2010 Location: GBT, Michigan Posts: 488 iTrader: 0 reviews	The Royal Purple was 75w and the Valvoline was 80w. That's the only thing that I could think of, that I shouldn't have added the friction modifier with the RP. The car is fine now with the Valvoline. No binding anymore.

April 18th, 2011, 08:50 PM	#9
NatesGT Regular 1996 GT Vert not sure yet Join Date: Jun 2010 Location: Tennessee Posts: 105 iTrader: 0 reviews	I have a buddy that had a 240sx sr20 det motor in it. Pushing around 450hp to the wheels. The car ran great was a freakin beast. He put RP oil in at the next oil change, and within a week threw a rod. Thats the only experience ive been close to with RP.

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