Modern cooling systems are picky about chemistry. Color alone is not a reliable way to identify a coolant. The owner’s manual lists the specification you need, and mixing the wrong technologies can shorten water-pump and radiator life. Treat this page as general background, not a substitute for that manual.
What coolant is doing
- Heat transfer from the engine to the radiator.
- Freeze and boil protection, usually as a mixture with water.
- Corrosion and cavitation protection for aluminum, iron, copper alloys and seals.
Types, at a general level
Coolants are often grouped by additive technology. You may see conventional inorganic-acid formulas, organic-acid (OAT) formulas, hybrid organic-acid (HOAT) formulas and others. Heavy-duty diesels sometimes also involve supplemental coolant additives (SCAs), unless the product is labeled as fully formulated and does not need them. Powersports equipment may specify a different product than a passenger car. The names and colors vary by brand; match the specification in your manual, not the dye color on a store shelf.
Checks you can do
- Check the level on a cold engine at the overflow tank markings. If the tank is empty, have the system inspected for leaks before you keep driving.
- Inspect hoses and the radiator cap for cracks, swelling or seepage.
- Test freeze protection with a refractometer or test strips designed for your coolant type, and compare the reading with the climate you park in.
- Watch for rust, oil or sludge in the tank. Those need diagnosis, not just a top-off.
- Replace coolant at the interval in the manual, which may be in miles, hours or years.
Safety
Coolant is toxic to people and pets; clean spills and store it locked up. Never open a hot radiator cap. Running the wrong mixture, or plain water alone in freezing weather, can crack an engine block. Dispose of used coolant at a household hazardous waste facility or parts store that accepts it. Never pour it down a drain.
For winter driving prep beyond the cooling system, see winter vehicle prep. For ATVs and similar machines, AMSOIL also lists a powersports coolant; confirm fit with the manual and lookup.
Frequently asked questions
Can I mix different coolant colors?
Color is not a reliable guide. Some coolants of different colors are compatible; many are not. Follow your owner’s manual, and if you are unsure, flush and refill with the correct type rather than mixing.
Is a 50/50 mix always right?
Many pre-mix products are 50/50, and many concentrates are mixed about that ratio, but follow the product label and your manual. Extremely cold climates sometimes use a different ratio within the range the manufacturer allows.
How often should coolant be changed?
Use the miles, hours or years interval in your owner’s manual. Extended-life coolants still have a limit.
AMSOIL coolants
- AMSOIL Heavy-Duty Antifreeze & Coolant. AMSOIL says it is a “ethylene glycol 50/50 pre-mix formulation,” is “fully formulated : DOES NOT require the use of supplemental antifreeze/coolant additives (SCAs) or extenders,” and provides “protection up to 1,000,000 miles, 20,000 hours or 8 years, whichever comes first.” AMSOIL also says it is “compatible with all other antifreeze and coolant colors.” Confirm that it meets your manual’s specification.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant. AMSOIL says it is “concentrated – requires mixing with distilled or high-quality water,” and lists protection “up to 150,000 miles (240,000 km) or 5 years” in passenger cars and light trucks.
- AMSOIL Powersports Antifreeze & Coolant. AMSOIL says it is “pre-mixed 50/50 with high-purity water” with “freeze protection down to -34°F (-37°C).”
Product wording above is quoted or summarized from amsoil.com. Read each product’s label and data sheet for directions.
Use AMSOIL’s official lookup guide to see what is listed for your vehicle or equipment.