Protect the cooling system of your Powerstroke diesel with the Ford Motorcraft VC-8 Diesel Cooling System Additive. Different engines require different chemical concentrations in their coolant. Proper levels of nitrite and silicate are what give Motorcraft Coolant its ability to protect your Powerstroke Diesel engine. Many other coolants do not have the necessary nitrite and silicate levels. Motorcraft Supplemental Coolant Additive recharges depleted silicates and nitrites in the cooling system. FEATURES: 1-Pint Bottle (473mL) Meets Ford Spec: ESN-M99B169-A For Diesel Engine Cooling Systems Ford Suggested Use: 7.3L Engines - With Motorcraft Green Coolant, add Diesel Supplemental Coolant Additive every 15,000 miles. 6.0L Engines - Use Anti-Freeze Test Strip Kit to test for coolant quality every 15,000 miles. Add Coolant Additive as needed. 6.4L Engines - Use Anti-Freeze Test Strip Kit to test for coolant quality every 20,000 miles. Add Coolant Additive as needed.