Like the human body, fluids are the lifeblood of your engine and can either contribute to the wellness of your system or be the cause of its demise. Here is what you need to know including maintenance tips for the fluids in your engine’s system.
Engine Coolant
What you should know:
For boats with a closed cooling system, always use the appropriate mix of water and antifreeze. Although your favorite NASCAR team might be using plain distilled water in their car’s radiator, because it actually has better cooling properties than antifreeze, it doesn’t have its corrosion-fighting properties. Besides, your boat doesn’t even have a radiator; it uses a heat exchanger instead that employs raw water, not air to cool the antifreeze mix.
Maintenance tips: Observant boaters have probably noticed that their car’s antifreeze is green and their boat’s is pink. That’s because autos use ethylene glycol, which is highly poisonous (4 ounces can kill a human). The pretty pink stuff is propylene glycol, which is far less toxic and is usually premixed with water so it can be glugged directly into the heat exchanger. Antifreeze can last several years, but change it if it becomes badly discolored or has a strong odor.
Potable Water
What you should know: The first order of business is never to put any water into your tank that you haven’t tasted first. When filling, let the hose run for a while to purge it of water that’s been sitting in it. If you don’t use your boat’s water very often, dump it every month or so and refill to prevent it from fouling.
Maintenance tips: Should it go funky, you can do one of two things: Buy a chemical mix named Puriclean, or use regular Clorox bleach. If using chlorine bleach, add 6 ounces for every 10 gallons of water and run your tap until you smell the bleach coming out. Shut the spigot off, leave your system pressurized and wait six hours before flushing the system.
Power Steering Fluid
What you should know: Because it operates in a closed environment, power steering fluid only needs to be replaced every five years or so, unless the color has changed. If it gets dark, chances are you have deteriorating seals or hoses. Check it occasionally to make sure your level is adequate, but the system doesn’t “use” fluid, so if you have to regularly top it off, you have a leak somewhere that needs to be corrected.
Maintenance tips: Although many engine manufacturers make and recommend that their brand be used, most are interchangeable with automotive brands. In an emergency, automatic transmission fluid can be used, but you should never use brake
Lower Unit Oil
What you should know: Probably the biggest bone of contention is how often to change the gear oil in your lower unit. It gets confusing when you consider that some car manufacturers have no recommendation at all for when to change it. Some manufacturers use sealed units that don’t allow it to be changed. Boats are different; they operate in a much harsher environment, and lower units can leak and allow water intrusion.
Although Evinrude doesn’t recommend that you change gear oil on its outboards more often than every three years, most builders call for it to be replaced once a year. Perhaps of greater importance is that you check your gear oil every so often throughout the season. Should it resemble a Starbucks’ au lait in color, it means water has found its way in and it can be a very serious problem if you don’t correct it immediately – usually by installing new seals.
Maintenance tips: When you do change gear oil, always use the marine formula recommended by the manufacturer and remember to replace the fill and vent screws to ensure a perfect seal. Unlike you would have guessed, you always fill it from the bottom of the two holes to make sure all air bubbles are evacuated.
Gas
What you should know: Much of today’s fuel is E10, which is “enhanced” with 10 percent ethanol, or moonshine, as they call it Down South, which is relatively harmless when it’s fresh and burned within a month or so after pumping.
But since ethanol attracts water and mixes readily, this can cause serious problems if the water/ethanol solution becomes greater than a half percent, which can happen due to condensation within your vented tank. Then a nasty little thing called phase separation occurs, which can create serious problems for your engine. What happens is the water/ethanol mix detaches from the gas and sinks to the bottom of your tank. If you run your tank low enough to burn this mixture, your engine will run extremely hot. Simply adding fresh fuel will do nothing to remedy this situation because once phase separation happens, like true love, it’s forever.
Maintenance tips: The only thing you can do when phase separation occurs is to drain your tank of the old fuel and refill. But you can prevent fuel from going bad in the first place. Most boaters know to add a fuel stabilizer like STA-BIL when decommissioning their boat for the winter (or in the summer if you are a snowbird). STA-BIL also makes a marine formula for year-round use that will counteract many of the ill effects of ethanol-laced fuel and also fight corrosion and keep intake valves and fuel injectors cleaner for better performance.
In addition, always use a 10-micron water/fuel separator filter, made by companies such as Racor and Yamaha, which not only separates water from your gas, but also removes tiny particles of debris before they enter the combustion chamber.
Transmission Fluid
What you should know: What transmission fluid, you ask. Outboard owners might not know it, but if you have power trim and tilt, you probably have it. If you notice your trim acting up, check your fluid level first. But make sure the engine is trimmed all the way up or the fluid will come squirting out. If it’s golden in color rather than red, your system uses gear oil instead of transmission fluid. Read the manufacturer’s recommendation before topping it off.
Maintenance tip: For inboards and sterndrives, change it yearly, or every 1,000 hours of operation, or sooner if it appears contaminated.
Oil
What you should know: The number one rule is to keep it at the proper level, so checking the oil should be high on your pre-launch checklist.
The other issue is changing the oil when you should. Most of us have bitten on the recommendation from companies such as Jiffy Lube that we should change our auto’s oil every 3,000 miles (most manufacturers say 6,000-7,500 miles). But traveling at 70 mph translates to only 43 hours of driving. In addition, you typically tax your car’s engine far less than the average boat motor. You shouldn’t treat your boat motor with any less respect.
Maintenance tips: The suggested interval for most four-strokes is to change the oil every 100 hours. But if you don’t reach that milestone in a season (shame on you), make sure you change it at least twice a year, including once before winterizing. And don’t try to save a few bucks by using automotive oil, since it lacks the corrosion inhibitors of the marine formulation. Only use oil that has the FC-W designation from the NMMA for full protection. Oil filters should be replaced with every oil change.