Best Marine Antifreeze-Coolants

EVANS may seem pricy, but considering its waterless formula won’t degrade with age or corrode your cooling system, and works as an antifreeze down to -40°F, this is easily the best long-term investment for your marine engine.

Waterless coolant protects against corrosion and electrolysis. Dramatically reduced vapor pressure. Improves engine performance. Lasts the life of your engine.

Original Green Antifreeze/Coolant, Concentrated – 1 gallon

EVANS is a high-end, relatively expensive coolant.

Best Bang for the Buck

Zerex

Zerex has kept marine engines going for decades with its classic green formula, and this inexpensive, versatile, coolant is still a worthwhile budget coolant and antifreeze combo to this day.

Protects engine from rust and corrosion. Reduces risk of deposits in cooling system. Antifreeze works against freezing down to -34°F. Keeps engine from boiling over. Affordable.

Coolanol 50/50 Blend Performance Coolant – 64 oz.

Zerex works across the board as a coolant and antifreeze, but it doesn’t feature bonus protections offered by competing products.

Maxima

Fairly affordable, protects against freezing down to -34°F, and shields against rust and corrosion, we highly recommend Coolanol for smaller marine vehicles, or else using Coolanol may get expensive rather quickly.

Protects against rust and corrosion. Moderately priced. Extra-low freezing point. Biodegradable. Raises cooling system’s boiling point to 265°F.

Star-Cool Premium Synthetic PG Engine Coolant – 1 gallon

We wish that Coolanol was available in bottles larger than 64 ounces.

Star Brite

The best coolant and antifreeze for repairing slow leaks in your marine cooling system, as Star-Cool guards your engine against wider ranges of temperature extremes than competing brands.

Quickly reduces operating temperature. Non-toxic propylene glycol formula. Seals pinhole leaks. Protects against freezing temperatures down to -26°F. Promotes an engine’s maximum horsepower.

Antifreeze RV & Marine -50°F

A fairly pricy coolant, but its additional engine-protecting features makes Star-Cool a premium coolant.

SPLASH

SPLASH is top-tier marine antifreeze for colder climates because it safeguards against temperatures as low as -50°F, and it’s a safer nontoxic option for use around children and pets too.

Impressive -50°F antifreeze protection. Biodegradable. Nontoxic. Great for winterizing marine vehicles. Prevents corrosion. Inexpensive. Large 1-gallon bottle.