I think 5w30 is what the motor was designed forTrack day is irrelevant. Motor is designed for 5W40 and that's all you really need. Unless you've rebuilt or replaced all the internals; in which case you should use whatever weight your engine builder recommended. Otherwise, the 40 weight is more than up to the task of anything you can throw at it. A lot of people worry about temps, which is a legit concern on the track, but remember your oil is the proper viscosity up to 212°. If you're seeing temps higher than that, you need to address the temperature, not the viscosity.
All good!! 40 probably wouldn't hurt anything other than a slight decrease in mpg... maybe****, ****, ****...you're right. I meant 5W30. I meant what ever weight the motor is designed for. I misspoke. Thank shineboy...great catch. Going back to edit. Had 40 on the brain for some reason.