I just had my open diff plate welded at PBM and I'm deciding on an oil to pour into it. The car is used 50/50 between street and drift miles. I'm looking for an oil that will happily survive the high temps found in a Z33 diff while lubricating the ring and pinion well. Being as it's not an LSD, friction modifiers are irrelevant. This means I want an open diff fluid. Very few people drive open diff Z's on tracks etc. so it's hard to find a well-tested open diff oil.

I see that Redline makes a 75W90NS gear oil, which is the same as the 75W90, but with no friction modifiers. In my searches I found many people liked Motul 300 as well.

What would you recommend? Bonus points for opinions from people who run welded diffs.

 

Any GL5 spec 75w90 will be fine. Good luck with a welded diff on the street, though.

 

I used to run a welded R200 diff in my GT5 Nissan racecar. I found a synthetic 75-90W handled the high heat better than a conventional oil. In my case, Valvoline 75-90W synthetic worked well (particularly as they were a sponsor) and I would swap it out every other race.

 

Sweet, thanks for your responses guys. Is GT5 a road racing class? What sanctioning body is it under?

 

SCCA runs GT5:

http://www.na-motorsports.com/Organi...ing/Rules.html

 

Yes- GT5 was a small-bore sedan class that transitioned to GT Lights (GTL) several tears ago. I currently run T3 in a 350Z, but don't use a welded diff in that class.

 

That's really cool. I bet you're a very good driver after racing momentum cars for so long.