Back when Mike first got his truck, someone said they read in the owners manual, might have been Mike, that high test would perform better. So, I called the dealer. They told me the factory calls for regular in the 2.7, and they could not recommend anything else. My 01 Tahoe called for regular, and the manual explained that the engine was designed to run on regular and high test has more carbon in it, and would cause the engine to carbon up. Now, with the computer regulated induction systems, that may not be a problem. I'm running regular in mine because the 40-50 cents a gallon more for premium, times 36 gallons, plus mower gas, comes to $20 more every time I fuel up. I thought about trying non ethanol when I'm in WV, but it's almost a dollar more per gallon than regular at Royal Farms at home. I paid $2.39 my last fill up and my total was $88. That was the truck, walk behind, and a 5 gallon jug.