Both vehicles are in sig. Malibu has old school 4T45E 4 speed and the truck has the new 6L80E six speed. Both the Malibu and Silverado are daily drivers, but the truck sees LOTS of in town short mileage trips topped off with some light/moderate long distance towing of 19 foot ski boat plus the fam. Is Dexron VI a good enough successor to the previous Dexrons for my apps, or should I invest in a full syn ATF like Amsoil? I NEVER go over 50K between fluid flush/filter change (more like 40Kish). Thanks.