Originally Posted By: Gary Allan
Apparently when you go much lower than a 4.x base stock, volatility climbs substantially. Bruce cited this as a reason why he's pretty much on the floor when talking about an every day PCMO with any kind of longevity in use in our 0w-10 distractions.
You're limited on the physical amount of additives that you can add due to how much they alter the end blend visc. They're all packaged in their own carrier oil at a concentrated ppm level. So, if you need MEGA ADDITIVES and need to "make room" for it in terms of a lower base stock, you're going to have volatility. Not so much an issue for 5 qualifying laps.
Yep, that's what I was thinking. From a keeping metal parts apart perspective, you can use a really thin oil, so long as the engine can keep sufficient pressure present in the bearing and other critical places. But with the present "technology" of oils, when you get really thin, the oil is going to be prone to evaporation at a rate that would be unacceptable in street use.
I'm sure there's more to it than that. OTOH, remember that there are applications out there (but certainly not automotive) that use compressed air as the "lubricant" in their bearings. I wonder what the SAE viscosity of air is? Really, google "air bearings" if you don't believe this.