If you run a diesel engine, you need this stuff in your life! Royal Purple MAX-TANE works year-round in all types of diesel engines - light, medium, or heavy duty. It plays nice with any diesel fuel including #1, #2, biodiesel, and ultra-low-sulfur diesel. The formula is specifically designed for modern HPCR diesel injection systems that can be picky about additives. Here's what it does: cleans out gunk from injectors, combustion chambers, and intake valves; makes cold starts easier; can boost fuel economy by up to 10%; prevents fuel gelling in winter; and adds lubricity to protect your entire fuel system. It's safe for diesel particulate filters and catalytic converters too. Use 1 ounce per 5 gallons for maintenance, or 1 ounce per 2 gallons if you're dealing with performance applications or really dirty systems. Just don't pour it into diesel exhaust fluid by mistake! Trust me, your engine will thank you with better performance and reliability.