Gasoline without detergents: Since detergents maintain and clean your vehicle’s fuel system, using gas without it may result in build-up over the years. That’s why you’ll want to do your best to fill your tank at top-tier gas stations that make sure to add a minimum amount of detergent in their fuel. Retailers like BP, Amoco, Walmart, or 7-Eleven might not include detergent, so try to avoid them if you can.