Outboard Motor Oil

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.

Part of being a responsible boater is to ensure that your boat isn’t leaking outboard motor oil.  Not only will leaks and spills be a detriment to the environment, but some states will fine you for leaving a trail of oil.  Spills and leaks can be prevented by checking your motor before taking your boat out on the water.  Also make sure that your motor is tuned and bilges have been checked for oil leaks.

Additionally, you should also check weather reports, as overturned and submerged boats can leak fuel and oil into the water, killing fish and other wildlife.

You should change your marine engine oil and filter every 100 hours or every season, which ever comes first. This simple piece of maintenance is often overlooked because it is not quite as easy as changing the oil in your automobile. Following is a step-by-step process which you can follow to make the chore more bearable.

Equipment Needed:
• An oil filter wrench to fit each size of spin-on filter you have
• A box of Zip-Lock baggies large enough to hold an oil filter
• A wrench the correct size for your crankcase drain plug, and a pan shallow enough to fit under your engine if possible or,
• A dipstick-tube oil drain pump and bucket big enough to hold all the oil or,
• An oil drain pump permanently fitted to your crankcase drain plug and bucket
• A roll of paper towels
• New oil filter(s)
• A supply of fresh oil as recommended by your engine manufacturer

Step-by-Step:
• Run the engine(s) until warmed to at least 130 degrees
• Drain the oil using the pump, or into the pan
• Replace the plug or close the valve
• Loosen the oil filter on the engine until it can be turned by hand
• Put a Zip Lock Baggie around the filter, and unscrew the rest of the way
• Use a paper towel to catch drips from the filter’s mounting
• Seal the zip lock baggie keeping the filter upright
• Put it into the new filter’s box
• Using your finger, wet the O-ring atop the new filter with fresh, clean oil
• Screw on the new filter until just finger-tip tight
• Follow the manufacturer’s recommendation as to tightening with the wrench
• Re-fill the crankcase with new oil (see your engine handbook)
• Be sure to add a quart for the filter
• Wipe up any drips
• Start the engine and let it run a few minutes
• Checking to be sure oil pressure comes up and there are no oil leaks around the filter or drain plugs
• Dispose of the oil properly at an approved disposal facility

Depending on your engine type, how fast it could potentially go and how quickly it will burn through oil, you have several brands to choose from.  Some people align their engine brand with the oil (such as using Yamalube oil for Yamaha engines), and others shop around.  When I bought my boat, I posted on a message board to find out what people recommended and that worked out pretty well since I was able to go with a brand, though not corporately related to my engine, my engine runs of a premium rate.

Over time, saltwater can cause serious damage to any engine, even with the usage of the best outboard motor oil.  But this can be avoided by regular servicing and maintenance.

Using a boat in saltwater isn’t the issue as much as where has your boat been in between trips. The problem with saltwater in engines is corrosion, mainly if the engine is sat doing nothing, but with saltwater in the cooling system. If the engine is regularly serviced, and is flushed with fresh water when removed from the water or when not used for long periods, then you shouldn’t have a problem.

Short term effects can be blocking of strainers or pipework with salt deposits; long term is rust within the engine, which can cause a whole host of problems if allowed to develop.

One of the most overlooked problems that boat owners have is leakage.  Whether your vessel is leaking outboard motor oil or water into the interior, this is a serious problem.  Leakage can cause some severe problems if not detected quickly.  If an issue like leaks is ignored, it can cost you thousands of dollars if your boat is assessed.  Depending on where and what is leaking, repair can range from something that you can do yourself to calling a professional.  The key is to catch it before it becomes an expensive problem.