My '01 Cobra has been using a quart per three weeks of driving. I dont even put that many miles on it. Last oil change i did I used Castrol Edge 5w20 with no other additives and it has been going through it pretty quickly. The engine does have minor leaks but most definitely not a quart per three weeks worth. When I bought the Cobra 6 months ago I noticed it was consuming oil, then I topped it off with a quart of Synthetic Lucas Oil Stabilizer and it stopped the consumption. I prefer not to use Lucas Oil if i dont have to, think I should go to 5w30 instead?