Hi guys, First off I'm a complete newbie to this site and have spent hours upon hours researching/reading all the posts and I love it!! Now down to business... After years of owning turbo rotaries (cue the haters) I thought I'd get into an LS1 turbo and only today purchased a VX SS with a T04Z etc that's fully engineered and is 'authority' safe. Now everything is sweet as - car is great to drive and has plenty of low down torque and power. My question is as above in the title the previous owner runs 10-40 semi synthetic diesel oil in her!! Does anyone else do this? I've done some googling and found bits and pieces but nothing really in concrete. Anyone care to give me the heads up please.