Running T6 and I feel like it breaks down pretty quick (4k miles) and typewriter tick last damn near the entire oil life. Just have heard good things about the AMSOIL 15w40
What say you….. been running shell Rotella for the first few oil changes but not completely satisfied. Thinking of switching to Amsoil, thoughts suggestions????
2017 Sierra 2500 6.6 L5P
44,****** miles