Redline 75w90 now, it was stock.

For the heavy track use guys, you might try using a 75/140 weight synthetic gear oil. It holds up better to shearing and extreme heat as would be experienced inside that diff.

How would 75/140 do in a daily driver situation with some cold temps though?

I run the Amsoil Full Synthetic 5w30 w/Amsoil Extended Life EA Oil Filters. On both the Caddy and the LGT both of which see track time.

-mike

It would be just fine, as it would still act as a 75 weight when cold, so nothing really changes on that end of the spectrum. If someone is driving the car primarily on the street, and just an occasional fun track event, I would probably recommend the 75/90 weight.

Do you think these finned differential covers do anything for the cooling aspect if you can create a little baffle to direct air over it?
NISMO DIFFERENTIAL COOLING COVER FOR NISSAN 350Z

Obviously not as good as an active differential cooler but maybe useful for the occasional tracker?

In our transes and diffy we run 80-90 Amsoil Full Synthetic. The 140 may do ok in there but my Armada towing 11,500lbs doesn't even call for 140 in the rear diffy, although I know the rears on the Frontiers do.

-mike

I'll probably hit you up for some next time, in a couple months.

I'd planned to do exactly this...a couple custom air guides and the finned cover. Then I plan to go with some Redline higher-temp diff fluid.

Does the 370z burn oil like the high rev 3.5?

Hi guys, sorry to bring this thread back from the dead. I was wondering for track days, what is a good weight oil to run? I'm also running a GTM Stage II S/C. Hitting Laguna Seca in a month (December, Monterey CA temps). Sam at GTM said they put in Motul 15w50 in the car, but he suggested Mobil1 0w40. That's for the normal driving, but I'm wondering on a track day, what is a good weight to run?

I'm not sure how it would relate to oil temps and how hard you work on the engine, whether a 0w40 would be better, or something like 15w50? Thanks again!

Unless you are hitting the track a lot and hitting it hard the 0w40 is going to be your best bet. The 15w50 is better for a full time track car that sees elevated oil temperatures.

Thanks, I definitely appreciate it!

I think 15-50 is a bit thick, unless you are in extremely hot climates.

I would use 5-40 motul. I run that in my 2011 sti on the streets and for track days.

Mike

It also depends on how hard the car is being driven. A car that gets absolutely hammered on all weekend is going to need more frequent oil changes and general maintenance than a car that does 1 day of HPDE driving.

For most people, going to the next best fluid above OEM is going to do the job generally, and changing oil and diff fluid every 2-3 events is fine. As far as what weight for the diff, 15W50 is good for places like AZ, where we are. Otherwise stick to 0W40 or 5W40.