There are many different types of antifreeze available on the market, so it can be difficult to choose the right one for your boat. The most important factor to consider is the climate in which you'll be using your boat. If you live in a cold climate and will be using your boat in freezing temperatures, you'll need an antifreeze that can withstand these conditions. Some of the most popular options include ethylene glycol and propylene glycol antifreezes. These products are designed to protect your engine from corrosion and freezing, making them ideal for boats that will be used in colder climates.
If you live in a warm climate or plan on storing your boat during the winter months, you can use a less-concentrated version of antifreeze. These products typically contain less than 50% glycol and won't cause as much damage to your engine if they leak into the water. While they're not as effective at preventing freezing, they're still good at protecting against corrosion.
No matter what type of antifreeze you choose, make sure to follow the manufacturer's instructions carefully. Overfilling your engine with antifreeze can cause serious damage, so it's important to only use the amount specified by the manufacturer.