Engine Coolant — OAT, HOAT & Diesel Coolants

Engine Coolant — OAT, HOAT & Diesel Coolants

Engine coolant is the heat-transfer fluid that keeps engine operating temperature within the designed range while protecting internal cooling system components from corrosion, scale, and cavitation. Using the correct coolant type for your engine and replacing it on schedule prevents long-term damage to water pumps, radiators, heater cores, and engine block passages.

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Extended-life OAT (Organic Acid Technology) and HOAT coolants are the most common replacement fluids for modern domestic and import engines, providing 5-year or 150,000-mile service life compared to traditional green coolant's 2-year interval. Diesel-specific coolants with supplemental coolant additive packages are required in Cummins, Duramax, and Power Stroke applications to prevent liner cavitation and corrosion of cast iron components. Waterless coolants like Evans provide boiling points above 375°F and are popular in track and race applications where traditional coolant management is difficult.

What type of coolant does my vehicle need?

Coolant type is specified by the vehicle manufacturer and varies by engine material and age. Modern GM vehicles typically require Dex-Cool OAT coolant, Ford vehicles require a specific HOAT formula, and Chrysler vehicles use a HOAT or phosphate-free HOAT depending on the generation. Mixing different coolant chemistry types can cause gel formation and corrosion inhibitor breakdown, so always confirm the manufacturer specification before purchasing.

How often should I change my engine coolant?

Traditional green silicate coolant should be changed every 2 years or 30,000 miles. Extended-life OAT coolants like Dex-Cool are rated for 5 years or 150,000 miles under normal conditions. Diesel coolants with SCA (supplemental coolant additive) packages should be checked at each oil change interval with test strips and replenished when additive concentration drops below the minimum spec to maintain liner protection.

Find the right coolant at Black Ops Auto Works. Browse our exhaust systems, air intake systems, and suspension upgrades alongside your maintenance supplies.