Sonic Mustang

I've been using Royal Purple in the differential and Royal Purple ATF in the 3650 (it's spec'd for ATF) since 2004.

Nothing's blown up or welded itself together. My transmission shifts perfectly and I have no problems with the syncros. If I remember correctly, RP doesn't need friction modifier in the diff.

The02GT

This completly contradicts what I have been saying but there was a sale on RP and I ended up getting it ONLY because it was going to save me $10 over buying Mobil 1, otherwise Mobil 1 was going to go in it.

Sonic Mustang

So, RP is crap, but you're willing to risk imploding your differential for a lousy ten dollars!

The02GT

Yep, I should have said in the begenning that I dont trust/think their motor oil and transmission fluid is crap. Gear oil is whatever I can get on sale as it protects WAY less moving parts. I never said it would make anything explode.

Sonic Mustang

I never wrote anything about exploding.

WJL

Ok some i'm goint to change my rear wheel bearing tomorrow, I have a 98 GT with a Trak-Lok. Planning on replace Differential lubricant with Castrol Hypoy C Gear Oil, SAE 80W-90 (GL-5) w/ Trans-X Limited Slip gear oil additive (CRC Product). I know RP is the way to go bu t i have two kids in college.

Hanes manual states: "Trak-Lok axels add 4 oz. of friction modifier when oil is changed
Trans-X directions step 2: "Add entire content of tube to differential (7 oz.)

Any suggestions or advise