Are many using Rotella T6 and is it working well? I'm thinking it may be the best option for me. Over the years I've run a lot of different oils and generally prefer Eastern oils (paraffin base) such as Kendall, Pennzoil, or Quaker State when it comes to regular oils but am not as specific on synthetic oils. I really like Kendall but it can be a pain finding it when you're on the road. A lot of people I've talked to like Rotella T6 and it can be found almost anyplace that sells auto parts, even Wal-Mart, so getting it is a piece of cake. If I remember right, the owner's manual says 15W-40 at warmer temperatures and 5W-40 at cold temperatures (don't have the owners manual in front of me so that's from an old dudes memory...). The dealer says it complies with warranty requirements. Shell seems to only sell the T6 synthetic in 5W-40 and their application page says that's their oil to use in my 07 Sierra Classic (LBZ) at all temperatures. Over the years I've had a lot of training and experience with oils and other lubricants but all directed towards the Heavy Duty Automotive and Construction fields and it makes sense that the viscosity improvers and additives would work fine. Probably the only difference is that if someone was running extended intervals and oil analysis they'd get a shorter oil life on a 5W-40 than a 15W-40 (generally speaking, the wider the range of the viscosity improver the faster it breaks down towards the base oil weight). That being said, I'm not a Duramax expert and would like to know whether people using Shell Rotella T-6 synthetic in their Duramax are pleased with it and any additional insights.
