gear oil question

[TMMK Toy]

I finally got around to installing Gabe's rear motor mount this past weekend. Or I should say my friend installed it. During the process I lost some gear oil when we removed the axle. We managed to find a plug to stick in to stop the leak but prob. lost 1/2 a quart to 1 quart. Anyway, after the install my friend looked around his shop and did find some 75w-90 valvoline synthetic gear oil for lsds. I'm wondering if this was ok to use. It's the same weight but didn't know if the lsd part is any factor. It's usually used on the rear diffs of S2000s he told me. I was planning to drain it all and refill with Redline MT-90 like I always run, as I notice the shifting is a bit stiffer in the colder weather. Is this bad that we added this fluid or is it ok for my tranny? Thanks, guys. BTW, E153 here if you didn't already figure that out.

[mig0s]

If it's synthetic 75w90, it's gonna be OK no matter what brand. However, it is better if you drain it and refill with the Redline.