OAT stands for Organic Acid Technology and uses an additive pack which does not contain Nitrites for system protection like Prestone Command Heavy Duty Nitrite-Free Extended Life Coolant. The benefit of this formulation is that there is less concern for additive depletion and the coolant can have a longer service life if maintained properly. NOAT stands for Nitrited-Organic Acid Technology and relies on the OAT technology but with added Nitrites to meet certain protection requirements for OEM’s like CAT-EC1 specification.  The coolant must also be tested to ensure proper levels of Nitrites remain in the coolant to provide sufficient protection as the Nitrite is depleted over time. Prestone Command Heavy Duty Extended Life Coolant uses this technology to meet these protection requirements. Fully Formulated Antifreeze is a type of Inorganic Acid Technology that contains all necessary additives to protect heavy duty engines. These products typically contain the term “SCA” (Supplemental Coolant Additive) or Pre-Charged in the name like Prestone Command Heavy Duty Pre-Charged antifreeze. This coolant can have an extended service life with monitoring to ensure that sufficient additives remain in the fluid to provide adequate protection.