Is it a bad idea to run the same weight oil year round? im asking because im using Mobil 1 5-30 in my LT1 with 6k mile OCI, and I only put around 3-4k a year... the oil im using is said to be a little too thin for my motor. Btw im doing an oil change soon would Mobil 1 0w-40 be better or..... Mobil 1 10w-30 ...which is the same 30 weight 5w-30 is when its warmed up right?