Anti Freeze

Antifreeze for Boat Winterization 

Find premium, non-toxic boat antifreeze products that provide maximum protection against bursting and corrosion in cold temperatures.   

PowerBoatSupply.com has everything you need to prepare your watercraft for the frigid winter months, including:  

• Cleaners and solvents for winterization 
• Rugged boat covers 
• Winterization kits 
• And more 

How to Winterize an Outboard Motor With Antifreeze 

Antifreeze is among one of the most important boat winterization supplies you can have in your arsenal.  

Antifreeze protects the engine from possible moisture damage, as water remaining inside the engine and its components may freeze and cause a wide range of defects.  

When it comes to boats with outboard motors, winterization often involves the following steps: 

• Replace engine and gear oil with a fresh supply 
• Add a stabilizer to fuel 
• Add antifreeze and run the engine 

It’s important that the engine has sufficiently warmed up before adding antifreeze, as this ensures that the fluid has made its way through the engine completely.  

How Many Gallons of Antifreeze to Winterize a Boat Engine? 

Adding the correct amount of antifreeze for boat winterization usually depends on the size of your boat’s engine: 

• 50 hp (Small Boats) – One to three gallons 
• 50 to 200 hp (Medium Boats) – Five to ten gallons 
• 200 to 500 hp (Large Boats) – 15 to 25 gallons 
• Over 500 hp (Extra Large Boats) – 25 or more gallons 

Keep in mind that these are only estimations of how much antifreeze to use in your boat’s engine. In general, you’ll want to add 1 gallon of fluid for every 50 gallons of coolant you use in your engine.  

Along with adding the proper amount of antifreeze to your boat’s engine, you should also use fuel additives for winterization to safeguard the watercraft from cold temperatures while it’s stored for the season.  

Fuel stabilizers prevent the formation of harmful rust deposits, which can cause massive damage to a boat engine.  

How Much Antifreeze Goes in a Boat Holding Tank? 

In general, marine holding tanks usually require from four to six gallons of antifreeze to prevent issues during winter storage. However, there are a few other factors to consider when adding antifreeze to marine holding tanks.  

You’ll need additional antifreeze if you’re including the hot water tank in the boat winterization process (as opposed to simply draining the tank of remaining water). You should also consult your vessel’s owner’s manual to determine the size of your boat’s water system, as this can help you determine the precise amount of antifreeze required.  

PowerBoatSupply.com Has the Boat Winterization Products You Need 

In addition to products to protect your engine and holding tanks during the winter months, PowerBoatSupply.com also carries marine shrink wrap supplies, covers and tarps for winter preparation, and many other essential items. See our inventory for yourself or reach out with any questions about the winterization process.