I would definitely not run 5W20 on the track. I don't know how much difference the squirters make but if the oil gets hotter it's more of a reason to run 5W50 or at least something in between such as 10W40.
There are multiple threads that have covered this:
https://trackmustangsonline.com/threads/what-race-oil-should-i-be-running.13801/
https://trackmustangsonline.com/threads/which-oil-to-use-for-track-days-for-2011-mustang-gt.13454/
There are multiple threads that have covered this:
https://trackmustangsonline.com/threads/what-race-oil-should-i-be-running.13801/
https://trackmustangsonline.com/threads/which-oil-to-use-for-track-days-for-2011-mustang-gt.13454/