Outboard Motor Oil

What is oxygenated fuel?   Oxygenated fuel contains oxygen as part of its chemical makeup.  The purpose of fuel oxygenation is often to reduce carbon monoxide levels created while the fuel burns.  Usually oxygenates come in the form of gasoline additives, such as alcohol.

Some boaters are concerned with the possibility than an oxygenated fuel can harm their motor and interfere with the performance of their outboard motor oil.  Outboard motors can generally tolerate up to 10% alcohol content in fuels, which is the maximum amount allowed by the United States.

If it is a new motor, and it is attached to a new Evinrude boat (or a new-to-you boat), congratulations! You may have a question or two about the best care and feeding for this fine machine.  For instance, if you are dealing with a two-stroke Evinrude motor, you may be wondering what kind of oil to use. Their suggestions are XD30, XD50 and XD100 oil for two-stroke motors that are 1993 and newer.   When it comes to the grade of Evinrude outboard oil to use, 87 octane is the current minimum, but 89 octane is actually preferred.  Use of higher-octane fuels have not proven to provide any additional benefit, and may actually exacerbate hard starting conditions in hot weather.

If you are wondering about the proper ratio of fuel to oil for optimal performance in your Evinrude motor, a breakdown given on the company website is as follows: 1958 and prior used 20 parts fuel to 1 part oil; 1959-1963 used 24 parts fuel to 1 part oil; 1964 and newer use 50 parts fuel to 1 part oil.  High performance racing usage requires a ratio of 25 parts fuel to 1 part oil.  Finally, when it comes to gearcase oil type and capacity, refer to your owner’s manual for specifications. 

Two cycle oil for high-performance racing motors needs to contain a heavier synthetic base than most to protect the pistons and bearing that are under more strain from the rigors of racing.  High performance two cycle motors can include stock or modified motors, including snowmobiles, personal watercraft, Moto X motorcycles, ATVs, go-carts and certain outboard motors. 

Performance motor oils need to reduce friction and burn clean, because high performance two cycle motors run hotter than recreational outboard motors.   The properties of appropriate performance motor oil will also provide some protection against wearing of essential engine components.

When choosing between a two-stroke or four-stroke outboard motor for your boat, the features of each must be considered.  Two-stroke outboard motors are lighter in weight, less expensive, and often faster.   They are generally easier to repair and maintain, having a comparatively simple design that has been available for almost 80 years. Two-stroke outboard motors tend to hold their resale value, remaining in high demand in the used market. On the con side, a two-stroke outboard motor produces more pollution, smoke, are non-two cycle oil injection models, have a rougher idle than their four-stroke counterparts, and are sometimes harder to start.

Four-stroke outboard motors are cleaner, quieter, smoother, provide more fuel economy, and are often more reliable.   They are preferred by some boaters who run in lakes and rivers because they are generally accepted at any body of water. They do not run on an oil and gas mixture or generate as much pollution.  The negatives of four-stroke outboard motors include their high expense for purchase and repair and heavy bulk, which makes it complicated to transport or position in storage without the help of a stand.  Because the design for a four-stroke outboard motor is more complicated than its two-stroke counterpart, there are more parts to malfunction.   However, outboard motor production will be either four-stroke or very similar. The technology for the four-stroke outboard motor is always improving, and as time goes on, there is a higher percentage of qualified mechanics to perform any necessary repairs.  The current used market is very limited for the four-stroke outboard motor, though this is also growing as technology and training improves. 

*Note:  this comparison does not include direct fuel-injected two-stroke models.

Just as it is important to maintain your car’s engine for optimum performance, your boat requires a certain amount of care for consistent and smooth operation. Since an outboard motor hangs outside the hull of a boat, it requires special attention to prolong its life.  Caution when transporting your boat to the destination of your planned outing is extremely important.  The motor and boat trailer should be braced securely so that the motion of land travel does not cause permanent damage. 

Each time a boat is returned from a salt water excursion, the outboard motor should be flushed out with fresh water to prevent the pump and lines from corrosion.  Outboard motor oil and gas lines should be drained and disconnected before storing your boat for an extended period of time to keep the carburetor clean.  The area around the propeller and gears of the motor should be checked for cleanliness and excess water accumulation.  The pump inside the motor should also be checked to ensure the impellers do not look worn.  If all of these steps are taken regularly, your outboard motor should provide its best possible performance.

The viscosity of boat motor oil is one of its most important properties, as it measures how any given oil will flow.  Thicker oils will generally have a higher viscosity than thinner oils.  The viscosity of boat motor oil is essential for productive engine operation.

The numbers and letters on boat motor oil packaging refer to measurements that have been taken at specific temperatures.  A “W” means the oil meets viscosity specifications for winter use.  Multi-viscosity boat motor oils prevent the oil from thinning as it warms up because polymers have been added to prevent the oil from thinning.  It is wise to use multi-viscosity boat motor oil with the narrowest span of viscosity for the temperatures you will encounter—in the winter, for the lowest expected temperature, and for the summer, for the highest temperature anticipated. 

In addition to a good upkeep on your engine (such as regularly changing your marine engine oil), you also need to make sure your boat itself is clean.  It may seem like a superficial process, but if you take care of your boat, it will take care of you.

Some cleaners on the market can actually damage the sealant on your boat. The phosphorous contained in many cleaning products is difficult to rinse from a surface. That residue builds up eventually causing the sealant to soften, which then results in oxidation. Strong cleaners can do the same thing. Use these products to clean your motors or when removing oil or heavy residue. Go sparingly then rinse immediately.

Your boat propeller works by changing the engine’s power into a thrusting that moves your boat forward. Knowing how to do basic propeller repair and maintenance tasks can go a long way in helping you take proper care of your boat without spending excessive repair technicians’ costs. Ignoring the problem will cause more problems, not unlike not regularly changing your outboard motor oil. Here are some quick tips to maintain your propeller:

• Check the blades on your propeller for nicks or bent parts. These are all signs of propeller wear that typically signal time for a propeller replacement. Any problems with your propeller blades can hinder the job they do for you and can hurt the engine. If your propeller has worn blades, your engine can be damaged further by improper acceleration.
• Mold any dings out of your propeller. If your prop is just a bit dinged up after a tough sail or impact with an underwater obstruction, it is possible to simply reshape it a bit. It is best to make a mold of the original prop in new condition where the blades are still at their original angle, and then use this mold as a guide when reshaping your prop after impact.
• Make sure your hub is not slipping. If the propeller hub is the problem, your boat won’t move at all even when you hit the gas. To fix this problem, remove the propeller, and mark the end of the propeller housing and the hub and keep the marks in line with one another. Install a new propeller to see if that fixes the problem. If the marks are out of line, your hub is slipping.
• Balance your propeller. This can usually only be done by a certified technician, but making sure your propeller is properly balanced ensures that it runs free of any troublesome or even dangerous vibrations.

It may be sometime before the season ends, but you’ll want to read up on the precautions you need to take to ensure a long life for your boat.  Prior to the step below, Drain the gear case and check for excessive moisture in the boat motor oil.

Then, flush engine with fresh water using flush muffs or similar device attached to the raw water pickup. Let all water drain from the engine. Wash engine down with soap and water and rinse thoroughly. Disconnect fuel hose and run engine until it stops. It is important to follow a step by step process to make sure that all fuel is drained from the carburetor to prevent build-up of deposits from evaporated fuel. Use fogging oil in the cylinders to lubricate the cylinder walls and pistons. Apply water resistant grease to propeller shaft and threads. Change the gear oil in the lower unit. Lightly lubricate the exterior of the engine or polish with a good wax.

Just like with your car, boat motor oil leaks can signal a problem. Find oil leakage can be indicated in several ways, whether it’s a pool in your garage or driveway or if it’s mixed with water when you remove the water plug.  Here are some things you should look at to surmise a leakage problem:

• Check your dipstick before and after you take your boat out. It’s also good practice to do this anyway.
• Check if there’s oil in the oil pan.
• Check the level in your tilt and trim reservoir.
• Change your filter, if necessary.

If you’re still having issues, consult a professional boat mechanic to see if there are any other parts of the boat you may have glossed over.  The main thing is to solve this problem immediately before it causes a great deal of damage to your boat.