The Best Gas For Your Boat's Performance

Choosing the right gas for your boat is essential for reliable and optimal performance on the water. The type of gas you should use depends on the type of boat you have. For example, small boats and pontoons usually run on gasoline and ethanol, but larger boats may require diesel. The make and model of your boat's engine will also determine the type of gas you should use. For instance, if you have a 2-stroke outboard engine, you will likely need to use a mixture of gas and oil. On the other hand, newer boats with 4-stroke engines get their lubrication from oil in the crankcase and do not require oil to be mixed into the gas. Additionally, it is important to consider the ethanol content of the gas. While E10 (10% ethanol) fuel is generally compatible with most boat engines, ethanol can corrode rubber and fiberglass, attract water, and cause other issues. Therefore, it is recommended to use ethanol-free gasoline or fuel with a low ethanol content whenever possible.

Ethanol-free gasoline

Ethanol can cause serious damage to boats over time. It can corrode rubber and fiberglass, clog fuel lines, and even puncture fuel tanks. It also attracts water, which can cause internal corrosion and uneven performance. Due to these issues, experts recommend draining ethanol-gasoline blends from your tank if your boat is docked for more than 90 days.

Overall, while ethanol-free gasoline may be more expensive and harder to find, it is the best choice for protecting your boat engine and ensuring optimal performance.

Oil and gas mixtures

Some boat engines, especially smaller outboards and 2-stroke lower-horsepower models, require a mixture of oil and gas to lubricate the engine's internal moving parts. This is because these engines do not have their own separate lubrication system.

Mixing Ratios

The mixing ratio of oil to gas depends on the particular model of the boat engine. Common mixing ratios (gas:oil) include:

• 25:1 (typically during the break-in period)
• 50:1 (most common)
• 100:1

To achieve these ratios, you will need to perform some basic calculations. For example, for a 50:1 gas-to-oil ratio, you will need to add 2.6 fluid ounces of oil per gallon of gas.

It is essential to find the correct ratio of oil to fuel to prevent issues such as smoking motors, hiccuping performance at high RPMs, and even significant internal damage. Many boaters pre-mix their gasoline before filling up to avoid an imbalance.

Types of Oil

Only use marine oil that meets the TC-W standard for this mixture to get the best performance and longest life out of 2-stroke engines. Marine oil, particularly from the original engine manufacturers, is designed to deal with the higher RPMs and the proximity to water sources in the marine environment.

Where to Find Oil and Gas Mixtures

Marine gas oil

MGO is similar to diesel fuel but has a higher density and does not need to be heated during storage. It has a transparent to light colour and is marked with Solvent Yellow 124 dye when used in inland waterway shipping. MGO has a lower viscosity than heavy fuel oil (HFO) and can be easily pumped into the engine at temperatures of around 20°C.

MGO is considered a low-sulphur fuel oil (LSFO) and is less polluting than HFO. Due to regulations by the International Maritime Organisation (IMO) banning the use of fuels with a sulphur content above 0.5%, many vessels are switching from HFO to MGO. MGO emits less particulate matter and soot than HFO, and its sulphur content can be more easily kept low. However, MGO is significantly more expensive than HFO, which is still predominantly used in commercial shipping.

Diesel engines

Another advantage of diesel engines is their longevity. Gasoline engines are made up of many more parts and are therefore more likely to break down. A well-maintained inboard diesel engine can last around 5,000 to 8,000 hours before requiring a major overhaul, whereas the average marine gasoline engine will only run for around 1,500 hours before needing similar work.

However, there are some downsides to diesel engines. They are louder than gasoline engines, which may detract from the boating experience. They are also more expensive to purchase and maintain, and diesel exhaust has a stronger and more unpleasant odour.

When choosing between diesel and gasoline engines, it is important to consider the size of your boat, your intended usage, and your budget. Diesel engines are typically found in larger boats due to their increased power and efficiency, but they may not be necessary for smaller boats or those used for recreational purposes.

Fuel and engine compatibility

Types of Marine Fuels

The most common types of marine fuels available for boats include:

• Ethanol-Free Gasoline: This type of fuel is marketed as REC-90 and is suitable for marine and small engines. It is designed to protect against the corrosive effects of ethanol, which can damage engine components. Ethanol-free gasoline is more expensive and may require a thorough cleaning of fuel tanks and lines if switching from other fuel types.
• E10: This fuel contains up to 10% ethanol and is safe for most boat engines. It is widely available and inexpensive, but it can corrode rubber and fiberglass, leading to clogged fuel lines.
• E15: This fuel contains 15% ethanol and is not recommended for boat engines due to its negative environmental impact and increased risk of phase separation and internal corrosion.
• Oil and Gas Mixtures: Some boat engines, particularly smaller outboards and 2-stroke lower-horsepower models, require the addition of oil to their gasoline. The oil helps lubricate the engine's internal moving parts and improves smoothness.
• Marine Gas Oil (MGO) and Marine Diesel Oil (MDO): These fuels are used in large commercial vessels and are not commonly found at marinas.

Choosing the Right Fuel

When selecting the appropriate fuel for your boat, it is essential to consider the type of engine and its specific requirements:

• Consult the Owner's Manual: The owner's manual will provide guidance on fuel and oil specifications, helping you choose the right type of fuel for your engine. Following the manual ensures reliable performance and compliance with the manufacturer's warranty.
• Engine Type and Size: The fuel choice often depends on the type and size of the engine. Smaller boats typically use gasoline or gas and oil mixtures, while medium-sized boats may use gasoline, gas and oil mixtures, or diesel. Larger commercial boats usually have diesel engines.
• Ethanol Levels: Ethanol can have corrosive effects on engine components and attract water, leading to performance issues and damage. It is generally recommended to use ethanol-free gasoline or fuel with no more than 10% ethanol (E10) in marine engines.
• Octane Rating: Different engines have specific octane requirements. Most engines can run on 87 octane, but some high-performance or higher-horsepower engines may require higher octane ratings, such as 89 or 91.

In summary, choosing the right marine fuel for your boat's engine is essential for optimal performance and longevity. By consulting the owner's manual, understanding the engine type and size, considering ethanol levels, and selecting the appropriate octane rating, you can ensure fuel and engine compatibility.

Frequently asked questions