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The Best Marine Antifreezes

Written by Anthony Roberts / Fact checked by Jonathan Larson

Winterization is one of the most important maintenance requirements for boats. It involves draining excess water and the use of the best marine antifreeze. It protects against chilling temperatures, preventing potential damage to the engine and other parts that can burst in extremely cold environments.

best marine antifreeze

Also known as a coolant, a marine antifreeze contains propylene glycol that raises water’s freezing point. The non-toxic formula inhibits the freezing of liquids, which minimizes the chances that the engine will crack or burst, even as temperatures begin to drop. It also has anti-rust and corrosion benefits, helping maintain the boat engine’s peak condition and performance. Aside from protecting the engines, antifreeze is also often used in a boat’s potable water system.

If you have no idea about the right boat antifreeze to buy, keep reading and learn from some of my recommendations.

<strong>Top 1</strong>

Splash 619526

+ Easy to use
+ Non-toxic formula
+ Provides excellent value

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<strong>Top 2</strong>

RecPro RV Antifreeze

+ Excellent burst protection
+ Contains corrosion inhibitors
+ Can be used even on steel, copper,…

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<strong>Top 3</strong>

Star Brite Non-Toxic Antifreeze

+ Dyed three times for excellent visibility
+ Made by a trusted brand
+ Comes as a pack of six gallons

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Top 10 Marine Antifreeze Reviews

1. Splash 619526 RV/Marine Antifreeze

With this marine antifreeze, I don’t have to worry about storing my boat in the winter. It can protect my engine at a temperature as low as -50 degrees Fahrenheit while offering effective burst protection as long as the solution is not diluted in water.

Ease of use is one thing that I love the most in this boat engine antifreeze. I don’t need to dilute the solution, which means that I can use it directly out of the bottle. All that I need to do is dilute any fluid before using this product. Otherwise, the antifreeze dilutes, which lessens its effectiveness.

If you want value for the money, it is hard to go wrong with this product. It is in a one-gallon container, which is more than enough for what I need in winterizing my boat. Aside from quantity, the quality is also notable, so I can get the best bang for the buck.

I can feel confident that I’m safe when using this antifreeze as it comes with a biodegradable formula. This is a lot safer compared to products with ethylene glycol. Its main ingredient is propylene glycol, making it non-toxic to both humans and animals.

If there’s one problem with this antifreeze, it would be that the bottle easily leaks. The cap isn’t too secure, so it spills easily without proper handling, especially during shipping.
  • Effective burst protection up to below -50 degrees Fahrenheit
  • Easy to use without the need to dilute
  • Provides excellent value for the money
  • Comes with a non-toxic formula
  • Bottle is easily prone to leaks
From its economical perspective of one-gallon quantity to its non-toxic biodegradable formula, this winterization antifreeze is a must-have for boat owners.

2. RecPro RV Antifreeze

Even in harsh environments, I don’t have stress about damages on the boat’s engine block and other parts where I can use this RV & marine antifreeze. It has rated protection of up to -50 degrees which means that it can protect against extreme temperatures.

It does not contain toxic chemicals that can make it unsafe for humans and animals. All of the ingredients are approved by the FDA, so I am not concerned that they are toxic.

More than being safe for humans, it is also safe on different materials, so I am not risking damage to my boat’s engine and its parts. Whether on steel, copper, brass, or plastic, it isn’t harmful. Plus, it does not use alcohol which prevents the rubber and plastic components from drying out.

A common problem in boat engines is that they are prone to corrosion during winter storage. With the cold weather and moisture, different parts can corrode when they are not used for a long time and exposed to water and air. Good thing, this antifreeze works as a corrosion inhibitor, minimizing the possibility of irreversible damage.

However, you can purchase this antifreeze only in bulk – either in a pack of two or four. If you have a small boat and do not need too much, it may not be economical.
  • Excellent burst protection even in the coldest climates
  • Made using materials FDA considers safe
  • Can be used even on steel, copper, brass, and plastic
  • The alcohol-free formula does not dry rubber and plastic parts
  • Contains corrosion inhibitors
  • Only available in bulk
Offering exceptional burst protection even in harsh winters, this marine antifreeze has a safe formula that does not harm different materials and components.

3. Star Brite Non-Toxic Antifreeze

When looking for marine antifreeze for engines, this is one product that should be on the top of your list. It is from Star Brite, one of the trusted brands in the market for marine care. This is already a compelling reason to trust its effectiveness.

I commend this antifreeze because of its visibility. It was dyed three times, giving the liquid a bright pink color. This means that even from the header’s engine, I can easily see if there is enough antifreeze.

Safety is another asset of this marine and RV antifreeze. With virgin and UPS-grade ingredients, it has high-quality and non-toxic components. It protects without harming my boat’s engine and other components.

Speaking for ingredients, it is safe for different plastic types, as well as for copper, aluminum, and brass. It is also safe even for rubbers and hoses. Additionally, it has premium additives that inhibit corrosion of the engine’s metal components.

This is also excellent if you are looking for value for every dollar. The price might initially seem high, but take note that this is because your purchase will come with six containers, each containing one gallon of antifreeze.

While the label says -50 degrees Fahrenheit, technically, it offers engine freeze protection only in temperatures ranging from 12 to 16 degrees Fahrenheit. This means that in negative temperatures, it isn’t enough.
  • Made by a trusted brand
  • Dyed three times for excellent visibility
  • Uses USP-grade and virgin ingredients
  • Contains premium additives that act as corrosion inhibitors
  • Comes as a pack of six gallons
  • Does not offer freeze protection in negative temperatures
This marine antifreeze has an extremely bright color for ease of visibility, offers corrosion protection to metal parts, and uses virgin ingredients to guarantee safety.

4. Sanco Industries Propylene Glycol Antifreeze

While I use this mainly as an antifreeze, I love its versatility—the manufacturer markets this propylene glycol solution as a multi-use product. You can also use it for making soaps, lotions, sanitizers, and moisturizers.

With a minimum purity of 99.7% and containing zero alcohol, you don’t have to worry about its safety. The main ingredient is propylene glycol, which is an excellent alternative to ethylene glycol, a common chemical you will find in inferior antifreeze products.

It is also a good thing that it has a certified food-grade formula. It does not contain ingredients that harm humans and animals. Nonetheless, we recommend that you store and flush the liquid as directed by the manufacturer.

The syrup-like consistency of this antifreeze makes it effective for lubrication. While the manufacturer does not specifically market it as a lubricant, I believe that it effectively reduces friction, minimizing damage to the moving parts.

While it might be a small problem, some of you might hate its pungent smell. Especially if you have a sensitive nose, the strong odor can be quite irritating. This is despite the product marketed as being virtually odorless. Some users also did not like the crystal-clear color, unlike others that are pink. Being transparent, it isn’t easily visible when used as an antifreeze.
  • Has many uses beyond being an antifreeze
  • Made of pure and non-toxic ingredients
  • Certified food-grade makes it safe for humans and animals
  • Comes with a syrupy consistency for lubricatio
  • The unpleasant smell can irritate some users
  • Has a crystal-clear color that makes it poorly visible
With a minimum purity of 99.7%, this non-toxic antifreeze has numerous other applications, such as making soaps and lotions.

5. Mercury Mercruiser Extended Life Coolant Antifreeze

This Mercruiser antifreeze promises extreme protection against freezing, even if the temperature goes as low as -34 degrees Fahrenheit. Gone were the days when harsh winters bother me since I am confident that this product will prevent my engine from bursting.

It is perfect for impatient boat owners. It is in a 50/50 pre-mixed formula, which contains deionized water. I don’t need to mix it with other products or dilute it in water. I can use it straight out of the container, making it user-friendly.

Looking at the label, one thing that catches my attention is the line that says it can provide extended protection of up to five years. I am in no position to say if this is indeed true since I haven’t used it for five years. Nonetheless, this is one thing that feels assuring to know.

A common issue with many antifreeze units is gelling. They become runny and less consistent over time, which can sacrifice their effectiveness. Fortunately, this antifreeze will inhibit gelling. By maintaining its consistency, I am more confident that it works as advertised.

Nonetheless, this product has minimal reviews online. If you are the type of person who relies on user reviews to decide if one product is good or not, it is disappointing to find a shortage of information on the internet.
  • The pre-mixed formula makes it ready to use out of the container
  • Provides extended protection of up to five years
  • Prevents gelling to ensure its consistency
  • Protects against freezing at up to -34 degrees Fahrenheit
  • Minimal reviews are available online
Promising good protection for up to five years, this pre-mixed marine antifreeze prevents gelling and offers effective freeze protection up to -34 degrees Fahrenheit.

6. Splash Marine Antifreeze

If you have a large boat or in need of a non-toxic antifreeze for multiple applications, this is an economical option. It is packaged in a 55-gallon drum, making it the largest of all the products in this guide.

Whenever I use any product on my boat, I look at its safety, not just for humans but even for aquatic life. I love this propylene glycol marine antifreeze because it is safe for incidental contact with humans and animals. I don’t have to worry that I am polluting bodies of water. It has plant-derived additives without toxic effects.

With this antifreeze, I can enjoy burst protection of up to -50 degrees Fahrenheit. This way, even in extreme freezing temperatures, the engine will not burst. This is effective in the prevention of cracks and other structural damages.

Aside from being safe, I also like how the formula is ready to use. It does not need dilution. Right out of the container, I can pour it directly on the engine or in any other component that I would like to protect from freezing.

While being in a 55 gallon can be a good thing if you are thinking about being economical, it can also be a drawback. Especially if you only have a small boat, it is too much, and storage is a headache since it comes in a large drum.
  • An economical option for large applications
  • Safe even for aquatic life
  • Has burst protection of up to -50 degrees Fahrenheit
  • Has a ready-to-use formula
  • Comes in a large 55-gallon container
In sum, this antifreeze in a large container offers excellent burst protection in extremely cold environments while ensuring a non-toxic formula, even for aquatic life.

7. TRUEGARD Marine Antifreeze

Most of the products I mentioned in this guide protect against bursting at a maximum temperature of -50 degrees Fahrenheit. This antifreeze propylene glycol stands out because of its maximum protection of up to -100 degrees Fahrenheit. Even in extremely cold environments, this can deliver a high level of effectiveness.

The safety of this antifreeze in both plastic and metal parts is also worth highlighting, especially in water supply systems. Plus, it has rust and corrosion inhibitors, making it good for preventing damage to metal components. The manufacturer guarantees its protection against corrosion for up to 12 years.

I can use this beyond boat water systems, and I am assured of its highest level of effectiveness. According to the manufacturer, it is also for swimming pool filtration systems, RV water systems, and travel trailers, among other things.

Each container of this antifreeze guarantees the same consistent level of effectiveness because it has been through computerized blending using high pressure. This ensures the right quantity of all the ingredients, depending on what the formula requires. It is custom blended to meet the exact specifications.

Like the antifreeze mentioned above, this product comes in a 55-gallon drum, which can be too much for some users. The drum size can be an issue for those who do not have the space to spare.
  • Maximum protection of -100 degrees Fahrenheit
  • Safe for use on plastic and metal components
  • Formulated with effective rust and corrosion inhibitors
  • Suitable for a wide array of applications
  • Has been through computerized blending for accuracy
  • Too much antifreeze for most users
Whether in metal or plastic, this large antifreeze offers superior protection. Aside from preventing freezing and bursting, it also inhibits rust and corrosion.

8. Prestone Original Marine Antifreeze

Like the product above, it also offers burst protection at up to -100 degrees Fahrenheit. Even when you are in a tremendously freezing environment, this antifreeze shields potable water systems from cracks.

When in cold temperatures, a boat’s waterline suffers from rust and corrosion. The latter speeds up structural damage and results in significant and expensive replacements. Using this product is a great preventive measure.

I am also a fan of this product because it is safe on different materials. I can use it on elastomers, rubbers, metals, and plastics. It does not contain ingredients that can damage such materials.

The pink color of this antifreeze is also a good thing. This makes it easily visible, which confirms the presence of the antifreeze in the system after it has been repressurized. You can be sure that it is the antifreeze that is flowing out and not water.

Like most marine antifreeze products, it does not require dilution. I can pour it directly into the water system. There is no need to mix it with other products to ensure its effectiveness in freeze protection.

Before using this marine antifreeze, take note that it is not designed for gas or diesel engines. It does not work on operating engines. Instead, it is only for water lines in boats, homes, pools, and RVs.
  • Guaranteed not to burst at -100 degrees Fahrenheit
  • Safe for different materials
  • Delivers superior rust and corrosion protection
  • Easily visible pink color
  • Not for engines
Wrapping up, this waterline antifreeze is safe on different materials, protects against rust and corrosion, and offers burst protection even in extreme temperatures.

9. Camco Mfg. 30757 Marine Antifreeze

Some antifreeze units wreak of chemical smell. With this product, there is no strong odor that is reminiscent of toxic ingredients. Aside from being odorless, it also has a non-toxic formula. I can use it even without a mask on since there is no unpleasant smell. Safety isn’t a concern with this antifreeze.

The price of this marine engine antifreeze is one more thing that I love. It is perfect for budget-conscious buyers. The pack comes with six one-gallon containers, which will last a long time. Even until next winter, I am sure that I will have enough coolant. As it is common with antifreeze, it has an indefinite shelf life, as long as the bottle is unopened.

Algae growth in an engine is a common problem that confronts many boat owners. Good thing, the effective formula of this antifreeze protects against algae. This makes sure that there are no obstructions that can limit the performance of my boat.

More so, it also acts as an effective lubricant. It can lubricate different components, ensuring smooth functionality. By reducing friction, it also minimizes potential damage. Especially when used in pumps and valves, I love how it provides the necessary lubrication.

Although it’s just a minor con, some might not like how it is a bit expensive. If you are on a budget, you can find other one-gallon alternatives at a lower price.
  • Has a safe and odorless formula
  • Comes in bulk with six containers
  • Inhibits the growth of algae
  • Lubricates components for a smooth functionality
  • Not for people on a budget
This pack of six antifreeze bottles is an exceptional product because of its odorless toxic formula, protects against algae growth, and helps lubricate different components.

10. Autozone RV/Marine Antifreeze

Straight out of the container, I can use this antifreeze. It does not need dilution. I can use it full-strength, eliminating the need for mixing. Do not use it with water or any other liquid since this can minimize its effectiveness.

I don’t have to worry about the accidental spillage of this marine antifreeze. While it has a bright and easily visible color, it does not cause staining. This is unlike other inferior products that leave an oily and sticky residue that forms hard to remove stains.

Aside from being non-staining, I also love the odorless formula. Without a strong smell, it is easy to apply. I do not need to wear respiratory protection since it does not have a pungent odor. Despite such, I recommend using it in open or well-ventilated spaces.

This product is not rated for winterizing engines. Instead, it is formulated only for water supply systems. It works on different pipe materials, including metal and plastic, except acetate.

The price of this product is one of its selling points. It is one of the most affordable on this list. Even if it is budget-friendly, it has a quality comparable to many of its more expensive counterparts. More so, it comes in a one-gallon container, promising the best bang for the buck.

In case you are like me who invests time in product research before making a purchase, this antifreeze can be quite a disappointment. You will find minimal information and not enough reviews to convince you that this is a good product.
  • Can be used full strength
  • Has a non-staining and odorless formula
  • Safe on different pipe materials
  • A great option for people on a budget
  • Lack of user reviews online
The non-staining, odorless, and full-strength formula of this marine antifreeze promises superior protection for winterizing my boat.

What is a Marine Antifreeze/ How Does It Work


An antifreeze does exactly what’s in its name – it prevents freezing in extremely cold temperatures. This is essential for winterizing boats, as well as potable water systems, swimming pools, recreational vehicles, and other things that can be damaged by harsh climate.

It is a liquid with a bright color, often pink or red, which lowers the freezing point of the liquid. From engines to pipes, different parts burst when they freeze because of the tremendous cold. This will prevent cracks and other damages.

While water acts as a powerful coolant, it is prone to freezing. When the temperature dips, water freezes. An antifreeze effectively alters the composition of water. It prevents the formation of crystal structures. Being chemically inert, an effective antifreeze also prevents rust and corrosion in metal components.

Types of Marine Antifreezes

Before buying an antifreeze, take note that they exist in different types. One of the best ways to categorize them is to look at the ingredients. This is indicative not only of effectiveness but also of safety.

Ethylene Glycol Antifreeze

This is for automotive applications. It is not recommended for marine use. While it is effective, it contains toxic chemicals. It is unsafe not just for humans but also for animals, aquatic life, and the environment in general. Despite this, some people still often use boat antifreeze ethylene glycol because it offers better freeze protection.

Propylene Glycol Antifreeze

If you are looking for a safer alternative, you should go with non-toxic propylene glycol antifreeze. Unlike ethylene glycol, it does not contain unsafe ingredients. Some are even marketed as food-grade. Even if it leaks in the water, I am not worried that it harms aquatic life. It is a more expensive option, but it is worth every dollar given its benefits and safety.

Benefits and Drawbacks of Using a Marine Antifreeze


The biggest benefit of using a marine antifreeze is that it protects against irreversible damages. From engines to pipes, it acts as an invisible shield that prevents crystallization. Otherwise, ice will form, causing different components to explode or burst.

Depending on the antifreeze that you will be using, it can also inhibit rust and corrosion. With water and moisture getting in the different parts of my boat, the corrosion rate significantly decreases, prolonging the life and improving the performance of my boat’s engine and other parts that the antifreeze protects.

Aside from burst and freeze protection, the antifreeze also effectively lubricates the engine and other moving parts. By reducing friction, it ensures a smoother functionality while also putting lesser strain on the components, making them longer-lasting.

Honestly, we cannot name any drawback of using a marine antifreeze. It can be an added cost, but such should not be a problem given the many benefits that it can deliver.

Buyer’s Guide

With plenty of options for a marine antifreeze, below are some of the most important considerations to help you narrow down your choices.


One of the most important is to consider the ingredient list. The most crucial is propylene glycol, which will make a non-toxic and biodegradable antifreeze. Some people also prefer one that does not contain alcohol.


I highly recommend choosing an antifreeze with a bright color, such as pink. This makes it easier to see the liquid, ensuring that there is enough to protect my engine and other parts of the boat that can freeze or burst.

Ease of Use

If you want an easy-to-use antifreeze, go for one that comes in the form of a pre-mixed solution. It should not require dilution or mix with any liquid. You must pour it directly into the engine, water systems, or anything else that needs winter protection.


Not all antifreeze products are compatible with your boat. For instance, some are only for water systems and are not meant to be used as antifreeze for marine diesel engines. Read the label before you buy and make sure that it is suitable for the intended application.

Maximum Burst Protection

This is one of the most important technical specs to look at. Often indicated in the label, the maximum burst protection is often -50 or -100 degrees Fahrenheit. Consider the lowest possible temperature in the area where you live as you decide on the best option.

Rust Protection

For the best bang for the buck, go for an antifreeze that protects beyond freezing or bursting. You will also find some that contain rust inhibitors. They are effective in minimizing the impacts of moisture and oxidation, not just to the engine but on the other parts of the boat as well.


Most will be packed in a one-gallon container. If you need more, you can also opt for a marine antifreeze 5-gallon container. Meanwhile, for large-scale applications, you can also find a marine antifreeze in a 55-gallon drum.

Care and Maintenance

Preserve the quality and ensure the effectiveness of a marine antifreeze by taking note of the things mentioned below:

  • Do not open the container unless you are ready to use the antifreeze. Most will have an indefinite shelf life when they are opened. Once you open it, however, it can be prone to external elements that might minimize its effectiveness.
  • Keep the antifreeze in the container that the manufacturer provides. Transferring it to another packaging can result in contamination. Most manufacturers package their antifreeze products with the best practices in mind.
  • Store in a dark place. Keep it away from direct heat, such as the sun and other heat sources. Keep it out of reach of children, especially if you have antifreeze with toxic chemicals.
  • Proper disposal is important when using antifreeze, especially for those that contain toxic ingredients. They can seep through the soil and harm aquatic life. Follow the manufacturer’s recommendations on how to throw the residual antifreeze.

Frequently Asked Questions


Who makes the best boat antifreeze?

Some of the most trusted names in the global market are Splash, RecPro, Camco, Star Brite, Prestone, and West Marine antifreeze. With the reputation of these companies, I am confident that their antifreeze products are safe and effective.

What is the difference between RV antifreeze and marine antifreeze?

When comparing marine antifreeze vs. auto antifreeze, one of the most important to note is the main ingredient, which impacts toxicity. Propylene glycol is the main component of a marine antifreeze. It is from two alcohol groups belonging to a class known as a diol. Meanwhile, an auto or RV antifreeze is often made of ethylene glycol, which is a toxic ingredient.

How long does marine antifreeze last?

A marine antifreeze has an indefinite shelf life in a sealed container. After opening it, however, air and dirt, among other things, can penetrate the liquid, resulting in minimal effectiveness. Use it as soon as possible. Pay attention to the color and consistency of the liquid to know if it is still good to use.

Where else can I use a marine antifreeze?

A marine antifreeze is versatile. Depending on the formula and the recommendations from the manufacturer, you can also use it for other applications, such as swimming pools, recreation vehicles, and septic tanks, among others.

How do you use marine antifreeze?

The procedures can vary depending on what the manufacturer recommends. We advise reading the label and religiously following the instructions in the container. Here’s how you can use antifreeze in your boat and prepare it for winterization:

  • Start by filling the tank with gas, which will prevent air. Otherwise, the air in the tank can bring moisture and condensation that can speed up rust and corrosion.
  • Next, add your choice of a fuel stabilizer. It will inhibit build-ups that can form over time when the engine sits idle during winterization or prolonged storage.
  • Run the engine for a few minutes, just enough to get it warm.
  • Add your choice of antifreeze. If you are using it in the engine, drain the engine block before pouring the antifreeze.
  • Aside from the engine, run an antifreeze as well on the other parts of the boat that are prone to freezing and bursting, including the air conditioning pumps, bilge pumps, and sump pumps.

How do you dispose of marine antifreeze properly?

Check the local authorities for proper disposal of marine antifreeze. In most cases, your marina will have a recycling facility. Otherwise, check the local council or ask around from other sailors about the procedure. Even if the antifreeze is non-toxic, do not just dump it in the water or ground.

Where can I buy marine antifreeze?

It is best to buy a marine antifreeze online. Apart from being convenient, it is easy to compare prices from different stores and brands. You can also read reviews from other people to help you decide. Some of the best websites to check are Amazon, Walmart, and Home Depot. You can also buy directly from the manufacturer.


Long-term winter storage can make boat engines prone to freezing, resulting in cracks and other irreversible damages. The best way to prevent this is to use the best marine antifreeze, including my recommendations above. Even if the temperatures get extremely low, you can be confident that your engine and other parts of the boat are protected. You can find more boat products such as ethanol fuel treatment or fuel additive on above of this article.

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