Just came back from a 400+ mile trip to the UP of Michigan and I noticed I went thru about 10oz. of Royal Purple. Never had a usage issue before. Oil is in the crankcase of a 2000 Z71 Silverado w/5.3L Vortec. I've used only synthetic oils from the first change (Mobil 1, PP, Castrol) once a year About 7K average each OCI. Engine only has 43K on it. I know 10oz. is not alot but I've traveled 1200+ miles to Florida and didn't have a drop in my level. Do ya think the RP was gettin to the places the other oils didn't (ie past the rings) I don't think I have the piston knock that these engines are prone to But maybe I do. Any thoughts...