Need quick reply GL-4 or GL-5 in rear diff?
 

So I'm going to change out the fluids in my BRZ and I got Red Line MT-90 75W90 GL-4 for both the trans and rear diff. From what I read the fluid will be fine for the trans but I can't seem to find if the GL-4 will be ok for the diff. If anyone can let me know I'd appreciate it. I searched but I couldn't find a clear answer.:thanks:

We tend to stick to GL5 for the rear diff if using Redline. The only other fluid we use is Motul 300 which is both GL4/GL5

for now I used Motul competition gearoil 75w140

Go with GL5