I mix the green stuff 50/50 with water. Just don't mix the green stuff with the orange stuff and you'll be fine. A friend of mine is still paying off the repair bill to fix what happened when Zippy Lube topped off her 2000 VW Golf with the wrong color. I think the lawyer will get it fixed in the end, but until then, she still has to pay the bills. Yet another reason I will never pay someone to change my oil...
Semper Fidelis,
Culprit