Choosing The Right Antifreeze For Your Boat Engine

Choosing the right antifreeze for your boat engine is critical to ensuring your boat operates properly. Boat engines are made of many important rubber parts, and alcohol-based antifreeze will dry out these parts over time, leading to increased maintenance costs. Therefore, it is recommended to use antifreeze formulas that are propylene glycol-based, such as the pink stuff, rather than alcohol-based formulas. Propylene glycol-based antifreeze is also non-toxic, which means it can be used to winterize your boat's freshwater system. It is important to note that antifreeze should not be used as a coolant in the closed portion of the engine cooling system. Coolant refers to a mixture of water and ethylene glycol heat-transfer fluid, which is toxic and must be handled with caution.

Antifreeze for Boat Engines

Alcohol-based vs propylene glycol antifreeze

When it comes to choosing the right antifreeze for your boat engine, there are two main types to consider: alcohol-based and propylene glycol-based antifreeze. Both have their advantages and disadvantages, but it is important to select the correct one to ensure the protection of your boat engine during winter.

Alcohol-Based Antifreeze

Alcohol-based antifreeze is a popular choice for many boat owners due to its low price and wide availability. It can be found in most hardware and marine stores, making it easily accessible. However, one of the main drawbacks of this type of antifreeze is that it can be highly flammable and should be kept away from any flames or lit objects. Additionally, alcohol can dry out the rubber parts in a boat engine, leading to increased maintenance and repair costs over time. Therefore, it is not recommended for long-term use in boat engines.

Propylene Glycol Antifreeze

Propylene glycol antifreeze, on the other hand, is a safer and more effective option for marine use. It is odourless, tasteless, biodegradable, and non-toxic, making it a more environmentally friendly choice. Propylene glycol is slightly more expensive to produce, but it offers superior protection against freezing and corrosion. It is safe for use in potable water systems and can also be used as a coolant for running engines. Propylene glycol-based antifreeze is the recommended choice for winterizing marine engines, as it won't cause any damage to the engine components.

Key Differences

The main difference between alcohol-based and propylene glycol-based antifreeze lies in their chemical composition and their impact on the environment and engine components. Alcohol-based antifreeze can be more harmful to the environment and can cause damage to rubber parts in boat engines. On the other hand, propylene glycol is a safer, non-toxic alternative that is better for the environment and can provide effective freeze protection without causing any maintenance issues.

When choosing between the two, it is important to consider the specific needs of your boat and the climate conditions it will be operating in. Propylene glycol-based antifreeze is generally recommended for marine engines due to its superior safety and performance, especially in colder regions. However, it is always advisable to refer to the manufacturer's guidelines and seek expert advice to make an informed decision.

Antifreeze for boat engine storage

Storing your boat for the winter without proper preparation can lead to serious damage. It is important to use the correct antifreeze for your boat engine to prevent this.

Firstly, it is imperative that you do not use automotive antifreeze in your boat engine. Boat engines are made with many important rubber parts that automotive antifreeze can damage. Alcohol-based antifreeze will dry out these parts, leading to increased maintenance costs as they will need to be replaced and repaired.

Always opt for a propylene glycol formula when choosing antifreeze for your boat engine. This type of antifreeze is non-toxic and specifically designed for use on boats. It not only prevents freezing but also helps to prevent rust and corrosion.

When selecting a boat antifreeze product, make sure it offers the right temperature protection. Antifreeze is rated by the temperature at which the gas line will freeze, not the ambient temperature. For example, a marine antifreeze rated for -50°F will only protect up to about -10°F, and freezing can start happening at around 15°F. It is recommended to select an antifreeze that is rated well above the coldest temperatures you are likely to experience.

Some recommended antifreeze products for boat engine storage include:

• Starbrite Non-Toxic Antifreeze: Provides burst protection and freeze protection within a range of +12°F to +16°F (-11°C to -9°C).
• West Marine Antifreeze: Offers protection for engines and fresh water systems.
• Sierra PG Engine Coolant: Provides freeze protection down to -26°F when mixed with water.
• Splash RV/Marine Antifreeze: Comes in a variety of pack sizes and provides protection down to -50°F.
• RecPro RV Antifreeze: A non-toxic option that provides protection down to -50°F.

The importance of regular coolant changes

Coolant is an essential component of boat engine maintenance. While water is the most efficient way to cool an engine, it has several drawbacks: it freezes in cold weather, boils in hot temperatures, and is corrosive to internal engine components. The solution is to use a coolant, which is a mixture of water and ethylene glycol. This not only addresses freezing and boiling issues but also prevents corrosion and the formation of limestone deposits and foaming. It further provides lubrication for pumps and other components.

However, using the wrong type of coolant or neglecting to change it regularly can lead to serious engine issues. For example, some coolants contain alcohol, which damages marine engines over time by drying out important rubber parts. Boat owners should also be cautious of using coolant with the wrong ratio of antifreeze to water, as this can lead to silicate gelling, where the silicate corrosion-inhibiting additive drops out of suspension, forming a clogging greenish goo.

To avoid these issues, it is important to use the correct type of coolant and to change it regularly. Most engine manufacturers recommend a 50/50 mixture of antifreeze and water for optimum year-round protection. This provides freezing protection down to -34 F and boil-over protection up to 228 F. Coolant should generally be changed every five years or after 1,000 hours of use.

When changing coolant, it is important to drain the old coolant and flush the system thoroughly before adding new coolant. This ensures that all the old coolant is removed and helps to dislodge any deposits that may have formed. Using distilled water is recommended, as tap water contains dissolved minerals that can react with and reduce the effectiveness of corrosion inhibitors.

By following these guidelines and maintaining their coolant systems, boat owners can ensure the proper operation and long life of their engines, avoiding issues such as deteriorated hoses, eroded water pumps, chronic overheating, and blown head gaskets.

How to check your coolant

To check your boat engine's coolant, you'll first need to ensure the engine is cool. Wait at least 30 minutes after the engine has been switched off, and if it has overheated, wait even longer.

Next, locate the expansion tank and coolant filler cap. Check your vehicle handbook if you're unsure where this is. The coolant should be between the 'min' and 'max' marks on the side of the expansion tank. If the coolant is below the 'min' line, you'll need to top it up.

It's important to use the right antifreeze for your boat engine. Don't use alcohol-based or blended antifreeze, as alcohol damages marine engines over time by drying out important rubber parts. Instead, use propylene glycol formulas.

When topping up the coolant, only do so when the engine is cold. Make sure to use the right antifreeze—different types don't mix well. Also, be sure to dilute the antifreeze with water at a ratio of 50/50. Distilled water is best, as tap water contains dissolved minerals that can react with and reduce the effectiveness of the corrosion inhibitors in the antifreeze.

If you notice any leaks, stains, or other problems, take your boat to a mechanic. It's not normal for the coolant level to drop, and this could indicate a problem.

Antifreeze for aluminium heads

When choosing antifreeze for aluminium heads, it is important to consider the specific type of coolant and the materials used in your engine. Here are some detailed guidelines and recommendations:

Choosing the Right Coolant

It is generally recommended to avoid alcohol-based or blended antifreeze for boat engines. Alcohol can dry out important rubber parts in marine engines, leading to increased maintenance and repair costs over time. Instead, it is best to use antifreeze with a propylene glycol base, specifically designed for engine cooling systems.

Aluminium Heads and Coolant Compatibility

Aluminium heads can be compatible with various types of antifreeze, but it is crucial to make an informed decision to ensure the longevity of your engine. Some sources suggest that the traditional green ethylene glycol coolant is suitable for aluminium heads. This type of coolant should be mixed with de-ionized or distilled water in a 50/50 or 60/40 ratio and changed every two years to maintain optimal performance.

On the other hand, some people have expressed concerns about the green coolant becoming "nasty" quickly and prefer long-life coolants. However, it is important to remember that any coolant, regardless of its type, should be regularly serviced and changed to prevent issues caused by acidic coolant.

Specific Coolant Recommendations

Several specific coolant brands and types have been recommended for use with aluminium heads. These include:

• Regular Prestone or its equivalent (ethanol glycol base)
• Sierra PG engine coolant (propylene glycol)
• West Marine antifreeze (for colder regions)
• Star brite Winter Safe -50 Degrees Nontoxic Antifreeze

Additional Considerations

When using aluminium heads, it is essential to consider the entire cooling system and take steps to prevent issues like electrolysis and corrosion. Some people suggest using a sacrificial anode in the cooling system to prevent corrosion of aluminium parts. Additionally, ensuring proper grounding of the radiator and heater core can help prevent corrosion issues.

In conclusion, when choosing antifreeze for aluminium heads, opt for a propylene glycol-based coolant designed for engine cooling. The traditional green ethylene glycol coolant, when properly maintained and changed regularly, can also be suitable. To enhance the performance and longevity of your cooling system, consider using distilled water for mixing and follow manufacturer recommendations for your specific engine.

Frequently asked questions