Modern motor oil designers have developed effective strategies for dealing with the negatives of polymers. Highest quality base stocks, tenacious additive packages containing just the right chemistry, and, yes, viscosity index improvers have now brought us super light oils that run clean, protect, and are capable of extended oil change intervals. I offer this conjecture as someone who has just finished up a 60k run on Sustina 0W20. The oil change intervals were 10, 15, 18, and finally 19k miles. The used oil analysis reports showed results that were better than adequate. The wear numbers were better than average. There was no thinning from shear or fuel dilution. The total base number stayed near 2.0 to 19k miles. This is similar to what happened with Mobil 1 5W30 in the famous Las Vegas taxi cab study. With regard to volatility, it was never necessary to top off my oil to 19k miles. After 60k miles the are no signs of piston ring coking or intake valve deposits. My engine is running very well.