Im interested in the QS powertrain warranty and buyback program for my Taco and 4Runner. I emailed them and included a copy of Toyotas verbiage allowing a thicker oil than 0w20 and they said in writing they will honor the warranty and buyback with the use of 5w30. That said I've not used QS full synthetic before and I'm curious as to how the 5w30 version holds up. Use will be 10k oci in both vehicles. Is this formulation pretty fair in terms of piston deposits and varnish protection etc? Any ida on a HTHS?