Would like to know your opinions on when to change to syntheic. I changed FF at 1000 miles with Valvoline 5-30 Conv. Next OC was 3500m with Valv. 5-30 Conv. Plan on running this until 7500m. Currently have 5500m on the 5.3L and want know if it's to soon to change to 5-30 Synpower on the next OC...
