Lol you are funny Helen' date=' anyway that was Mark you should of heard the things he was saying [/quote'] I didn't say nuffin! (that's my story 'n I'm stickin to it) I think the Shell stuff has more engine-cleaner-type additives than the Tesco fuel. I've noticed smoother running, especially on older cars with Shell. However I think if you drive your car properly (ie warm up and use all the rev range from time to time) it'll make very little difference which you use.