So I am going to change my diff fluid tomorrow at work, I used amsoil 75w140 before. This time, I bought motul gear 300 75w90. (no friction modifier, the LS version is with modifier)
Anyone else run this fluid on their diff. Because after seeing this post, I am a little concerned https://www.google.ca/url?sa=t&rct=j...VD4Ufe6caBvRPQ
I

 

I am using Amsoil 75W-90 Severe Gear in my differential and it is fine.

 

+1 here as well.

 

Was using Amsoil 75-W-140...now on Redline 75-W-140:much better,no more whine from my 4.56 gears.

 

I'm using it with no side effects. Thats both street and track. It was reccomended to me by 2 very fast s2000 racecar builders/racers.

 

I am currently running the Motul Gear 300 LS in my diff and tranny with no problems. I live in Utah and the cold weather didn't seem to affect it this last winter. I also autox my car. I followed the recommendation from the GT channel on how they set their car up for the track.

https://www.youtube.com/watch?v=n8mD...HU3Tw&index=18

How to Prep Your Car for the Track - Track Life Episode 1

 

LE 1605

 

Using a GL-5 gear oil designed for a differential in a transmission designed for use with a GL-4 tranny fluid is a horrible idea.

 

Not according to Motul. This is from their site.

GEAR 300 LS 75W90

 

Your link does absolutely nothing to show that you should be using this product in an S2000 tranny. GL-5 is not an improved version of GL-4. This isn't brake fluid.

Aisin designed this transmission around the same time they designed the 6-speed used in the NB Miata. Both are spec'ed for GL-4 fluid not GL-5. Do some research both here and on m.net and see the effects of long term wear that the increased sulfur content in GL-5 fluid has when wrecking havoc on your synchros.

GL-4 = tranny

GL-5 = diff