Zaxz28

My 2000 camaro got a gear swap from 2.73's to 3.73's, I believe I have a zexel torsion rear. The type of oil they put in it is bg ultraguard 75w-90 synthetic. Does anybody know if this is a good oil, or when I get my computer back from being tuned sould I have it changed. No friction reducer was added either, I have seen it on ls1 tech that some people do not think it is necessary for a torsion, but looking for opinions if I should add it.

Thank you

Zach