To maximize diesel power and performance we recommend that you use AR6400-D Diesel Fuel System Cleaner to provide a deep clean to your fuel system every 5,000 miles. You can then use AR6300 Winter Diesel Treatment (or AR6500 Diesel Treatment in the warmer months) at every fill-up between uses of AR6400-D. Both AR6300 and AR6500 boost cetane, improve fuel lubricity, and contain a maintenance dose of detergents to maximize fuel system performance at every fill-up.