I have a '01 Sierra with a GM 5.3L. With this bieng a LS1 drivative, I'm looking to run a little thicker oil in it. I only use the truck about 10K miles/year, so it sits a lot as well. I will change the oil twice/year. I was planning on using Rotella T Synthetic 5w-40. However, I'm wondering if I would be better off going with Mobil 1 0w-40? Just to complicate things, I was at AZ this evening and found a whole row of GC. Another point of concern is that this truck gets started just to move it out of the way in the garage, only to be turned off in the driveway and then restarted to move it back in. It does see highway driving when it is driven. What would be best for my truck. I plan on keeping it around for many years and miles.