I live in Denver, where there are massive temperature swings all year. It snows as late as May, but the track season runs almost all year and it’s totally possible to have a 80 degree track day in March.Except that isnt actually correct. Many people dont understand oil viscocity and most internet info is explained by people who also dont understand it. Not every oil that starts with a 0 will flow the same when cold. The 1st number does not directly mean "cold". A 0w20 will flow mich better at cold temps than a 0w30 or 0w40. Pick the oil brand of your choice and look at the actual specs on their website. All manufacturers have this info accessible. You will see that if you compare their 0w20, 0w30, and 0w40 oils their viscocity spec for 40c will get higher and higher. There are a lot of chemical factors at play here that I wont geek out over, but the mass understanding of how oil ratings work is wrong. What I can tell you with absolute certainty is that the farther apart you go with the 2 numbers in an oil rating like 0w40 the worse quality the oil becomes. It is very dependant on additives and modifiers to cover such wide viscosity ranges and those break down long before the base oil does. What you end up with is oil that is easily diluted, vaporizes early and does not lubricate well. Want to know why VW\Audi engines are notorious for carbon build up problems that everyone likes to blame on direct injection....? Its their crappy 0w40 oil combined with far too long oil change intervals.
What’s your thoughts on 5w-30 vs 0w-30 oil for track use?