so i decided to go with non syn, because from all the research i have done from nasioc, it seems that itll be better for my tranny and rear diff in the long run right? but the question is, where can i get redline 75w90? actually, i think imma go syn for the rear diff..using the redline 75w90s. its okay to go with two different types of gear oils right? i heard too many complaints about people using mobil one syn for the tranny and rear diff, so i think imma stay away from that one. does anybody else have any other input? i really just care about the longitivity of my tranny. my car hasnt seen the track or auto x, and probably wont for a while. any recommendations?

All Redline products are synthetic, the difference between 75W90 and 75W90NS Redline is the former has the friction modifiers and the latter doesn't.

you want the regular 75w90 for the rear diff - you would use the 75w90NS for the transmission (if you decided to go that way) - all redline products are synthetic.

To find a dealer, check their website (they have a dealer locater on it) - www.redlineoil.com

I use all Red Line in my engine and the tranny. I run ShockProof Ultra light in the tranny and rear diff. PM me if ya want to know where to get some...

I'm running Redline MT-90 in the tranny and shockproof in the rear diff. My tranny felt good with stock fluids for 35k miles and still shifts well. Actually downshifts better and can shift into first without coming to a near stop.

actually, where would i be able to get my hands on some 75w90 dino oil. do they have oem gear fluid at the dealership?

just checking in.. i recently switched to redline for the trans and rear diff. i put 2 quarts 75w90ns and 2 quarts heavy shock proof in the trans and used regular redline 75w90 in the rear diff. shifts alot smoother now, the entire drive train is alot quieter in general, i can get into 1st gear via rev matching at up to 30mph now whereas i used to have to be under 10mph and even then it was 50/50.

based on the research and dozens of threads i read before switching, i think the only problem people really have with using redline/synthetics in general is that they can be too slippery for the synchros to work properly. that is why i went with the mix of ns & shock proof. i dont expect i will have any problems with this combo as long as i dont abuse the gear box.

edit: you can pick up non-synthetic 75w90 at any auto zone/discount auto parts/etc. while it can vary from dealer to dealer.. i think most of them use valvoline which is one of the more common and readily available oils anyway.

Weitek- nice to see that someone also likes the mix of heavy and 75w90ns. I betting that in florida you dont really get the 20*F temps that make me have to be patient in the morning.

I completely aggree with wietek.

Give your Tranny a Strawberry Milkshake! :banana:

YMMV

nick

Do not use Redline75w90. Use their 75w90ns. The rear diff does not like having friction modifiers. The 75w90ns contains no friction modifiers.

thanks for the advice. do you have any threads or links to explain about that? i can switch out the rear diff if necessary... thanks

I've been using Redline 75W90 in the rear for about 40K, fine so far. I asked Redline for their recommendations before changing and they suggested 75W90 for the rear and NS for the trans.
Either way there is no effect on the LSD since it is a sealed viscous unit.

Mulders right- you really want the LEAST friction in your diff. In the tranny since the syncros work on friction you need some so that all shifts dont have to be rev-matched perfectly.

here's any article from cobb tuning regarding gear fluid.

http://www.cobbtuning.com/tech/gearoil/index.html

Heard redline shockproof is good stuff... --eric--

I read the Cobb article and switched about 23,000 miles ago to Redline MT-90 in the transmission and 75W90 in the rear.
I got the Redline from Jeg's online.
Shifting got better, and mileage improved fractionally. My only concern is Redline is GL-4 rated, and our transmissions are spec'd to use GL-5. For that reason, I may change to Neo 75W90 HD (Baker Engineering), but I'm not too concerned right now.

Originally posted by Mulder
I've been using Redline 75W90 in the rear for about 40K, fine so far. I asked Redline for their recommendations before changing and they suggested 75W90 for the rear and NS for the trans.
Either way there is no effect on the LSD since it is a sealed viscous unit.

Mulder, got a question. Saw you post this 2 days ago in response to a guy in a 98 Impreza w/a rear diff question:

"The 75W90-NS does not have friction modifiers. The 75W90 does have them.
The NS will work fine in your rear diff."

I've seen so much confusion here about NS fluid. My understanding is that you want to use NS in the rear diff...NOT THE TRANNY!

Sorry for singling you out Mulder, just wondering if you had a typo or not

No typo.
The friction modifiers reduce operating friction in the assembly the fluid is used in. For the rear diff, which consists of gears and bearings, this is a good idea. However the friction modifiers aren't essential, so either type of fluid can be safely used in the diff and you will still have the benefit of synthetic either way.
As for the transmission, the friction modifiers are a definite no-no so only NS should be used. The friction modifiers will interfere with proper operation of the synchros.

Does standard dino 75W90 have friction modifiers?

Usually not, but you have to read the label to know for sure what's in the bottle. Different brands may have different additives.