While visiting my local drug pharmacy I found some Citgo Supergard, Exxon Superflo 10w-30, and Shell High Mileage. The Citgo oil is SL and 2.89 a quart. The Exxon Superflo is the same price and the Shell HM is 4.15 a quart. My question is, are any of these oils worth messing with at these prices?