Shell Oil Co.
The new Shell ROTELLA DFA is an all-season diesel fuel additive to help keep injectors clean, prevent gelling, and improve cold starting. It improves the fuel’s cetane number by up to three points (a higher cetane number means easier ignition and quicker starts even at low temperatures). It exceeds Cummins L-10 specs for fuel-injector cleanliness and prevents fuel gelling down to -40 F, Shell says. It’s also claimed to increase power, reduce black smoke and soot, lubricate the fuel-injection system, disperse water, and increase fuel mileage. One 96-ounce bottle treats up to 300 gallons of fuel. It also comes in 32-ounce bottles. Its use is recommended every 10,000 miles during the summer and in every tank during the winter.