I was once thinking this myself and as i work at autozone, I thought I would give it shot. I used one quart of Lucas substituting one quart of oil. Now in theory this sounds good for your engine, with the goopy mass slowly ciculating your system... That doesnt sound like somthing we want(in the 1.6 anyway). I experienced a loss of powerband with my car losing most power around 5k rpm and the pull decreased as well. Without putting Lucas oil in your car you can find out for yourself real fast what it does to your engine. go to your local auto store that has the little 20% Lucas and oil vs just plain oil(it has the little crank for each and there are 4 gears that rotate). Now crank em fast and you feel that the normal oil has little resistance, but then crank the lucas and feel the goopy mass slowing down even those little gears. Just think what that would do in your engine. I would not recommend lucas oil for anyone unless you dont care about performance.