Limited slip additive

[Ralph]

Do I need limited slip additive for my 1971 dodge challenger.

8 3/4" rear end having new ring and pinion installed.

If so which one do I buy and where do I get it.

Thanks to all.

 

[Mopars & Missiles]

If you've got a "sure grip" in that axle, then Yes you do need it.

Go to your local Dodge dealer and get a bottle of the "real thing". They've got it.

 

[moparlee]

First of all, you don't have a limited slip, you have a Mopar Sure Grip. Yes you need it. Here's what Dr Diff recommends and is what I put in mine. You can also down to your local (hate to say it) Ford dealer and pick it up.
Friction Modifier for Limited Slip Differential/Posi/Suregrip

 

[Ralph]

Thanks to all

 

[Mopars & Missiles]

Here's the Mopar type. P/N 04318060AB

 

[tonysrt]

Is there any difference between the Ford and Mopar additive. We know Ford & Mopar don't make it, so it must be made by some oil Co.. Any other recommendations?

 

[Cudafor36]

Drive line works recommends KW which you can buy at advance auto. That's what is in mine now.

 

[aussiemark]

You can get dedicated limited slip diff oil usually called LS90 and it would probably depend on the type of locking unit used. Is it an after market or OEM unit? the modern Torsen style units use normal GL5 rated gear oil with no additive and the mechanical Detroit locker types prefer a mineral based gear oil with no additive apparently Eaton won't honour a warranty claim if synthetic oil is used, I prefer a proper oil over an additive use the additive in a crappy SUV not a muscle car.

 

[mmissile]

I've always used non-synthetic with the Ford modifier. Local shop that's been in business for 50 years ["Ring and Pinion"], always use the stuff for mopar/Ford rears. They're the best specialized shop in SE Mi.

 

[i_taz]

Never assume synthetic is better than dino oil. I put Mobil 1 in my '97 Dodge Ran Van and the pinion bearing of all things went out after <10,000 miles. I would follow mmissle's method. I even
put a shot of the Ford modifier in my tranny after the lingering effects of Wally World's synthetic transmission fluid caused a shutter in my '02 Ford pickup which should handle a synth fluid but not that one...!

 

[booyaballer]

can you add too much additive?

my 8.75 was rebuilt in april 2017 which has been leaking. i don't recall if i ever added the additive for the posi. if i add a bottle for good measure will that be bad or cause harm?

thanks.