Delvac been around for a long time no need to switch if it's working for you.Gosh, I never heard of Hotshots or Schaeffers until I purchased my diesel pickup and happened upon this HDEO forum. I just use the good old Delvac brand that my company used for years on our fleet vehicles. I had no idea of these fancy oils for a diesel engine (Mobil 1 excluded). I'm almost 2nd guessing myself on the 3,000 - 5,000 mile oil change intervals.