Oil Question

CZero

I use Mobil 1 racing 15w50.

You want a high viscocity for higher temps here in Texas as that is what protects the motor at higher operating temps, which the 370z definitely sees.
The W number has only to do with cold starts which are all tested below 0...

Oil's with viscocity of 0w40, etc are good for cold weather and cold starts, but act like a 40 weight at operating temps. the 0w stands for 0 weight in Winter conditions.



What makes ester oils good though is not their resistance to building heat, but their resistance to shearing, extended interval length, etc. They basically keep their viscosity rating through a broader range of their service interval length.

So when lesser oils are near the end of their service life, the viscosity of the oil is generally reduced compared to the advertised rating. This varies between oil types and brands. It can be quite disturbing with some oils to see just how far from advertised they become after a few thousand miles

So, really you should look at a high viscosity oil than 30 for this motor if you plan to mod it or drive it hard, etc.
Or not, up to you.