Skip to main content

How to Make Your Outboard Last Forever

A modern outboard will last a long, long time with only basic care and maintenance.

The September 2013 issue of Power & Motoryacht carried one of the most popular articles ever printed in this fine magazine. Written by Richard Thiel, How to Make Your Boat’s Engine Last Forever gave a number of tips to keep a gasoline or diesel inboard engine spinning happily for, well, maybe not forever—we’re talking about engines, not Stonehenge—but for as long as the boat lasts. That was Thiel’s definition of forever, and I think it’s a pretty good one.

With basic care and maintenance, modern outboards can go for thousands of hours.

With basic care and maintenance, modern outboards can go for thousands of hours. 

Now I’ll try to match Thiel’s advice, but with outboards. Is that even possible? Can an outboard motor run for 1,000-plus hours, like a big, slow-turning diesel can? Most folks would say no, but take a walk along the docks of any marina catering to smaller boats, and you’ll see plenty of well-used Evinrudes, Johnsons, Mercurys, Yamahas and others—and by “well used” I mean built in the 1990s or even earlier, but still taking their owners on fishing and family trips without incident. Okay, maybe some of these outboards look a little rough, but don’t we all as we get more hours on the clock?

I made a few calls to test my hypothesis. One person I spoke with, a charter fishing captain from eastern Long Island, has almost 6,000 hours on his Yamaha 150 four-stroke. The boatyard owner who lives across the street from my mom powers his workboat with a 1996 150 Evinrude Ocean Pro; it has at least 2,000 hours, and he admits he “beats the hell out of it.” A longtime friend, a respected pro in the marine industry, is obsessed with catching tuna on his days off; he just replaced his 19-year-old loop-charged 250 Evinrudes with a pair of 200 Yamaha four-strokes. This is a guy who puts so many hours on his engines, he buys his two-stroke oil by the 55-gallon drum. Why didn’t he buy new ‘Rudes? The E-TEC G2s are all digital, but he wanted to keep his existing steering and controls; the mechanical Yamahas let him do that.

All of these guys do two things to extend the lives of their motors: They keep up with regular maintenance, and they wage a constant war against corrosion. Outboards, diesels and inboards are more likely to succumb to corrosion than to overuse—but corrosion is easy to defeat. Keep it at bay, and a modern outboard motor should keep cranking for thousands of hours of operation. And when it comes to boats, as Capt. Thiel contended some years ago, that’s pretty close to forever.


Let’s consider the basic principle of outboard longevity: keeping up with regular maintenance. And that means RTFM, or Read The Friggin’ Manual. Everything you need to know—everything you can do without being a trained outboard mechanic—is in there, and the most important pages deal with routine maintenance schedules, as specified by the manufacturer. Follow these schedules religiously. Typically, this means changing the lower-unit lube every 100 hours (or at lay-up), and on a four-stroke, the crankcase oil, too. You can suck out the crankcase oil through the dipstick tube but changing the lower-unit lube means hauling the boat. Some manufacturers, like Yamaha, suggest changing the water-pump impeller at the same interval, which means dropping the lower unit as well. It’s not as big a deal as it sounds, but you might want your mechanic to do it. Service the thermostat at the same time; overheating shortens the life of any engine.


Evinrude E-TECs have a longer service interval than other outboards: five years or 500 hours for the latest G2 engines. Being two-stroke engines, they have no crankcase oil to change, and have fewer moving parts than four-strokes; that means fewer parts that need maintenance, and fewer parts to fail. Elaine Arsenault, senior media adviser at BRP (Evinrude’s parent company), said there are Evinrudes “all over the globe” with several thousand hours on the clock. In the past, common maintenance items such as spark plugs, water pumps, lower-unit lube and fuel filters were replaced on a yearly basis, even if they did not need it, she said. (Water pumps, for example, can last for hundreds of hours unless they suck in a lot of sand or other debris.) Ultimately, the proper care of the outboard—meaning service, replace when necessary, lubricate when recommended—extends the life of the motor. And, she added, outboards that are used more frequently are known to last longer.

E-TECs are sophisticated, with digital steering and controls and other interesting high-tech capabilities: For example, they can be winterized via the electronic control panel. Push “winterize,” and the engine runs for 90 seconds with double oil, then shuts down. You can do this in the water (don’t run the engine afterwards), or with a garden hose for cooling. There’s no excuse for not doing it right. E-TECs are a far cry from the 10-hp Evinrude I abused every summer in the mid-60s. (We were an Evinrude family, and my father wouldn’t let me have any other motor. Since then, I’ve owned two Yamahas, which would have Dad turning over in his grave if he hadn’t been buried at sea.) Funny thing about that motor—it only had two speeds, idle and wide-open.

Keep the Fuel Clean

Here’s another maintenance biggie. Change the fuel filters, the external fuel/water separator and the filter inside the cowling, at the proper interval, which is sometimes different from the oil-change interval. Some external filters can be drained, others have spin-off canisters that are replaced; some, like those from Mercury, have water sensors that warn you when the filter needs attention. If you don’t have an external filter/separator—one of the few components that don’t come packaged with the motor—mount one right away. Keeping water and gunk out of the engine is key to longevity, and the fuel/water separator should stop most contamination.

Even veteran DIYers find the need to call in the pros on some jobs.

Even veteran DIYers find the need to call in the pros on some jobs.

There are a couple of other things to keep in mind. First of all, before pulling apart the fuel filter under the cowling, remember it’s RTFM time again: On Mercury Verados, for example, there’s an inline filter on the high-pressure side of the fuel system, and the manufacturer recommends it be serviced by a mechanic every three years. Other motors get the filter replaced every 100 hours.

Also, never use gas with more than 10 percent ethanol, and always add a fuel stabilizer. In a perfect world, you’d use fuel wholly without ethanol, especially with older motors, but finding pure gas is problematic today. My tuna-fishing friend adds Ring Free to every tank of gas, as recommended by Yamaha. Not only does this extend the life of his motors, it puts him in a stronger position if warranty issues arise. Evinrude recommends their own 2+4 Fuel Conditioner, which helps dry the fuel, isolates moisture and slows the breakdown of ethanol-blended gas. Moisture in gasoline can cause corrosion even inside an outboard’s cylinders—not good if you want your outboard to last forever. Some warranties require using the manufacturer’s proprietary fuel additive, so, yet again, RTFM.

Go with the Correct Lube

As with fuel additives, always stick with the lubricants the manufacturer recommends. Each one has its own proprietary concoction, and it can be a warranty issue if you decide to fill ‘er up with Slippery Joe’s discount brand instead. Check the oil level in your outboard before each use, or at the end of each boating day. It’s easy on a two-stroke, but some four-strokes demand a multi-step procedure to get an accurate reading. With my pal’s Yamahas, for example, the procedure is to tilt the engine up fully for five minutes to let all the oil drain back to the crankcase, then lower it all the way, and wait another minute or two before pulling the dipstick. Don’t be alarmed if it comes out completely dry, he said; that just means there’s a vacuum in the crankcase. Pull the dipstick to break the vacuum, re-insert it, then check the oil level again. This should give you an accurate reading. If you just pull the dipstick after running an engine, without tilting it up and down, the oil level will read incorrectly low.

And don’t forget. Change the oil filter when you change the oil, and either send a sample off for oil analysis—I’d do this at layup time every year—or cut the filter open and check the paper pleats inside for “sparklies,” flecks of metal that shouldn’t be there. Oil analysis will turn up any contaminants in the crankcase oil. Poorly seated piston rings can let gasoline find its way into the oil, and oil diluted with gas ain’t good, especially in a four-stroke. Such an issue demands the attention of a professional mechanic.

When you change the lower-unit lube, also make sure to inspect the old, used oil. The magnet on the drain plug will catch any metal particles, but if the used oil is gray, there’s excessive metal micro-particles suspended in it—not a good sign. Moreover, whitish oil has water in it, which can mean a blown seal somewhere. In either case, it’s call-your-mechanic time again. Even if the oil looks okay, sending a sample for analysis is worth the few bucks it costs. Finally, check the compression at layup; better to discover a problem in November than during spring commissioning, when the fish are starting to run.

Make sure to inspect the old, used oil or send a sample off for analysis. 

Make sure to inspect the old, used oil or send a sample off for analysis. 

Flush It and Fog It

More engines die from corrosion than from overuse, and nothing promotes corrosion more than a combination of salt water and dissimilar metals. Replace all sacrificial anodes when they’re half gone; the manual will show you where they all are. Flush out your outboard with fresh water every time you use it. Heat and salt water combine to leave stubborn deposits in cooling water passages—don’t let them dry in place. Let the water run for fifteen minutes to rinse all the salt out. Even if you operate in fresh or brackish water, flushing is still a good idea to remove mud, algae or other contaminants from your outboard’s water passages.

Some people add a salt-removal solution to the rinse water—I’ve used Salt-Away, but Starbrite Salt-Off and Honda’s Salt Terminator are two others. Is this necessary? The pros I spoke with use plain water, but an additive is better at dissolving the salt crystals and leaves a polymer barrier to protect against future deposits. One tip, though, is to flush the motor while it’s still hot and the thermostat is open, so the rinse water, with or without additive, flows through the engine. Rinse the outside of the motor, too, especially under the mount where the tilt motor lives and salt can accumulate. Don’t be shy with rinsing, and use the anti-salt additive there, too; you can buy a gadget that fits on your hose nozzle and mixes the stuff with the spray water.

The final corrosion preventative? Pull the cowling, check for fluid leaks and rust, and then spray what you can see of the motor with an anti-corrosion liquid, something like CorrosionX, CRC or Starbrite Ultimate Lubricating Fluid. Do this every month if you operate in salt water, and at the end of the season when you winterize the motor. While these compounds won’t damage wiring or hoses, don’t spray any black boxes that look like they hold electronic brains. No sense tempting fate.

Will doing all of the above really guarantee mechanized eternal life? No, but following these basic preventive maintenance practices should keep your outboard running smoothly for more hours, weeks, months and years than you’ll actually need it, and that’s as good as forever in my book.

This article originally appeared in the November 2019 issue of Power & Motoryacht magazine.