Zenak

Rear Diff / Manual Trans:
RP vs Redline vs Amsol

Ok Im trying to come up with a consensus, tons of posts read...
nothing all in one spot. Concise. Which way to go?
Nothing consistent.
Screw Mobil 1, I have had no luck with it when doing HPDE, etc.

Rear Differential: 1.7 Quarts
Royal Purple: 75/90 Max Gear
Royal Purple: 75/140 Max Gear
Redline: 75/90 with Additive
Redline: 75/140 with Additive
Amsol: 70/90 Severe Gear oil EP

Manual Transmission: 3.6 Quarts
Royal Purple: Synchromax
Redline: MTL 70/80
Redline: Racing ATF Synthetic
Redline: D4 ATF
Amsol: ATF Dextron (ATFQT)
Amsol: ATD (ATD1G )

I use the car 10 months a year. I live up in the frozen north, Pennsylvania

It is a combination street use car and running about 10 HPDE/season & a few AutoX.

AlwaysInBoost

what kind of info are you looking for? with out an unbiased third party analysis of each oil anything you'll read on here is opinion. I'm sure an AMSOIL dealer will come in here and say there's is the best, then RP & Redline fans will claim theirs is the best... and mobil1 fans will also claim theirs is top notch.

I've used the ones above, whats currently in the car I have bolded. I've got samples of all of them sitting on the shelf but never got around to sending it out to Blackstone for analysis.

I don't think there is any BAD oil really, as long as you use the type thats intendend for the car. the key is frequent changes.

Zenak

how about the 75/90 vs the 75/140..

I have seen a preference both ways. No clue why?

I have used the RP now for 2 years, and have to say Im relatively happy with it. But it never hurts to create a nice conversation about it all in one place with the actual products listed exactly by name and model. I will also link this thread to my C5 Track Car thread later on :-)

dcvee

I've seen somewhere were the 140 was recommended over the 90 for "high preformance" use.

I've always used redline in my tranny's and diffs. I've also used Mobil 1 in the diff with good results.

Don

davidfarmer

I've always used Mobil 1 with absolutely no problems......... If you keep the fluids within proper range (ie use coolers), there is no need to go to a thick viscosity IMHO.

Zenak

anyone ever add zmax to the diff / trans?

shifter77

Tranny ROYAL PURPLE SYNCHROMAX , diff ROYAL PURPLE 75/90

Solofast

I had a bad experience with Redline in a Dana 44 on my C4. It was too slippery. We put Redline in it when we rebuilt it and it caused the clutch plates to wear out in a couple of weekends, where the OE GM factory fill lasted 3 years. Once clutch plates in a diff start to slip they wear out in very short order. This was in autocross use where we are very hard on the diff, so it might not be as appropriate for track use.

Bottom line is that super slippery lubes in the diff are a bad idea.