I own an '09 Silverado with the 5.3 with AFM. The manual stipulates the use of 5w-30 in order for the AFM to function properly. I drained the FF at 1k and am now running M1 5w-30 with a M1 filter. I have 6k on the truck now. Is it ok to run the German Castrol 0w-30 in this motor? I have read reports that it's a bit thicker than M1 5-30...so not sure if the AFM will function properly? I live in NH, and we get pretty cold winters up here. I am still reading up on old posts about GC 0w-30...but would appreciate any help. Thanks!