By: Ashley Lizzi on July 8th, 2022

What is Boat Gas? (Fuel for Thought)

Being prepared ahead of a day on the boat will ensure that things run smoothly and your entire crew enjoys their time on the water.  There are lots of things to consider before jumping on board including safety gear, boating accessories, snacks, and a well-stocked cooler.  

That said, there are very few items more important than boat gas.  An empty tank can ruin your day before it starts.  It can even lead to being stranded on the water which any boater can tell you, kills the vibe instantly.

The question is, are you prepared to deal with an empty tank before you leave the dock or in the middle of the day while out on the water?  Do you know what type of gas you need for your boat or where to get it?

Knowing what type of boat gas your vessel takes and where you get it is crucial for getting out on the water.  If you have a recreational boat tune-in, I’m going to share everything you need to know about boat gas in this article.  

What is Boat Gas?

The term boat gas is used as a blanket term for the gasoline that goes in boats.  There’s not one specific type of gas that falls under this term, but rather, it’s the gas that is appropriate for the engine that’s in or on your boat.

For recreational boats, there are a few different choices that will work for most.  Knowing which type of gas to use should start with knowing the exact engine you have and what’s best for the make and model.  

Fuel Based on the Engine

If you’re wondering what type of boat gas to buy, the first place you should look is in the owner’s manual for the engine.  The engine’s manufacturer will have the most accurate information about this topic.

They will also be able to tell you what fuel will help your engine reach peak performance.  Remember, not all fuel is created equal so it’s imperative that you’re going off of the manufacturer's recommended fuel type.

That said, most engines you will see on smaller recreational boats such as pontoons and speed boats use the same rule of thumb when it comes to fuel.  This will vary if your boat has a 2-stroke outboard engine, however.

What Type of Gas to Buy

As I mentioned, the type of gas you put in your boat will depend on the type of engine you have.  You will find that the motors in newer recreational boats all have similar requirements for fuel type.  It’s when you start mixing in older styles that this can change drastically.  

For instance, if you’ve got a 2-stroke outboard engine on your boat, you’re most likely going to have to find the fuel that is a mixture of gas and oil.  This type of fuel used to be more common at marinas but it’s becoming more and more phased out with newer engines on the market. 

Unless you have a 2-stroke outboard, newer boats are likely to have engines that do not require oil mixed into the gas.  For instance, many newer engines on the market are 4-stroke and get their lubrication from oil in the crankcase similar to your vehicle. 

So, if you know what type of engine you have and it’s not a 2-stroke the next question is what octane to go with.  Most engines will run just fine off of 87, but this isn’t the case across the board.  Some of the higher-horsepower engines require a higher octane, such as 89 or 91.

To be sure, check with your owner’s manual on the octane type you need to buy.  Some recommend higher octane strictly for peak performance and some require it.  No matter the octane level, there’s a common denominator you should be aware of.  

For these types of engines, there’s one main rule of thumb you want to use when buying gas for your boat and that is to avoid fuel that has ethanol in it.  Most recreational boat motors are not equipped to run well off of gas that has more than 10% ethanol blended in.

There are older boat engines that were built before fuel companies introduced ethanol into the mix and therefore they don’t tolerate it at all.  Some of the newer engines can tolerate a small amount of ethanol but it’s not recommended.

The reason for this is that ethanol draws moisture into itself.  So, if you’ve got ethanol in the tank of your boat, it’s going to be surrounded by water and now you’ve got a recipe for service issues.  If you run the boat with ethanol frequently, you run the risk of water getting into the tank due to that moisture draw.  

To avoid this, you should avoid buying gas for your boat that has any ethanol in it at all.  To to do this, let’s talk about the safest places to buy boat gas.  

Where to Buy Boat Gas

I’m going to say it and I know I’ve got fellow boaters out there that will cringe.  Your go-to stop for boat gas should always be the marina in your area.  Marinas will offer gas that is safe for all boat types which includes ethanol-free options.

In my experience boat gas on the water is always more expensive than filling gas cans up at the local gas station.  That’s why it can be cringeworthy for some, but paying the extra two or three dollars a gallon shouldn’t deter you from fueling your boat with the gas that will keep your engine running at its best which will be cheaper in the long run. 

If you don’t have access to fuel on the water, filling gas cans at the station in town might be the only way to go.  In that case, keep in mind that not all pumps are labeled if they have ethanol mixed in.  More and more you'll find that most marinas and many gas stations now sell a “rec blend” or recreational blend, which contains no ethanol.  If you’re at a gas station, look for the rec blend label and you’ll be in good shape.   

Gas Powered Boating

I hope you’ve learned that the first place you should turn if you don’t know what type of boat gas your boat requires is your owner’s manual.  Depending on the engine make, model or size, the type of fuel required may vary.

For many newer recreational boats today, an ethanol-free 87, 89, or 91 octane will do the trick.  If you’ve got access to an on-water gas station, you can count on the fact that they will have what your boat needs.

Keep in mind that if you run the appropriate fuel through your engine and have routine maintenance performed on the boat, that motor should run for years.  Maintaining the engine also means properly winterizing the boat when the season is over.

Keeping the engine healthy will help maintain the rest of the components on board.  Doing so should ensure that your boat will start right up when you drop it in the water at the beginning of each boating season.