Recently spoke with some old school car techs who swear by top cylinder lubes "added to the fuel tank" The explanation I got was that lube in the top cylinder "above the rings" can increase performance and FE. While browsing the local pep boys I came across top cylinder lube made by Lucas. It sounds good to me, what do you guys think. At 4 bucks per tank, it does not seem like a wise investment. In my case if I got 2mpg more, I would break even..