Spark Plugs: How To Get the Most for Your Money




Money aside, manufacturers of most internal combustion engines that use spark plugs explain how to inspect and/or change the plugs. Getting the most out of the plugs is never their focus; they’d rather urge you to buy lots of plugs and change them regularly. Your engines will get better mileage and last longer, say they.

Well, maybe so. I’m not convinced, but maybe so.

Newer motorized vehicles have all gone to using fuel injectors rather than spark plugs, so this post–unless you drive a vintage vehicle–is not about your family car or pickup truck. On the other hand, we own several gasoline powered portable generators, each of which features a single cylinder, a carburetor, and a single spark plug…and experience has shown us how to get the most bang for the buck in the plug department.

Simply put, I don’t change the plug on any of those engines until it’s missing so badly that we’re not sure it won’t just quit entirely at any second.

A waste of fuel, you say? That’s certainly what the so called “experts” try to tell us, but let’s take one specific example.

We run a total of four gasoline powered generators ranging in size from a little Yamaha EF2000iS (2000 watts) to a Steele 10,000 watt unit. Our pride and joy is the Yamaha; it produces pure sine wave electricity that is safe for electronics, and it’s also amazingly economical. A single gallon of gas will run all of our home’s lights, TV sets, and computers for eleven hours or more. Running at no load, which we sometimes have it do if we need to be gone overnight (just to make it sound like someone’s at home), it will keep going for more than fourteen hours.

And strangely enough, how frequently the plug is changed seems to have no bearing whatsoever on the fuel economy or the life span of the machine. The Yamaha is powering this computer as I’m typing, running like a dream with more than 18,000 hours of usage. I’ve spot checked that machine for fuel economy right out of the box, at one month of age, and at various points thereafter.

At every point, the generator performed like the Energizer Bunny.

Whether the spark plug is brand new or on its last legs, the engine starts on the first pull of the starter rope (except in noticeably cold weather, when it might ask for another pull or two). It gets the same outstanding fuel economy and produces the same risk free electricity.

These results are admittedly counterintuitive. You’d think a plug that looked fresh and ready to go would produce noticeably better results.

You'd think a spark plug right out of the box that looked fresh and ready to go would produce the best results.

You’d think a spark plug right out of the box that looked fresh and ready to go would produce the best results.

Yesterday, the Yamaha finally announced its readiness for a spark plug change. The engine had been missing a bit for some time, but hey, as long as a single fill of the small tank ran the machine through the night while I was up typing, what’s a miss or two between friends?

The owner’s manual doesn’t say just how frequently the spark plug should be checked. Rather, it sounds like a typical politician, refusing to be pinned down and using terms like “important” and “checked periodically”.

Okay, yeah, I check it periodically. This particular period was probably around one year, or perhaps as much as two years. As for the amount of usage, this spark plug had a bare minimum of 5,000 hours of run time, perhaps as many as 10,000 hours. The generator has more than 18,000 hours on it, and I’m pretty sure this was only the second spark plug change.

Can’t you hear all those experts hyperventilating?

The environmentalist types, too. Polluting the atmosphere with that worn spark plug, that would be their angle of attack.

But again, remember: There was never any measurable drop in either power output or fuel economy.

Now, are you ready? Eager to get a glance at the plug that could keep that Yamaha engine going for all those hours without ever giving up? The plug that could serve as the poster child for getting the most for your money from a spark plug?

Okay. Here you go.

This spark plug never quit.  The little Yamaha generator's engine was missing noticeably, but it still ran, minutes before this photo was taken.

This spark plug never quit. The little Yamaha generator’s engine was missing noticeably, but it still ran, minutes before this photo was taken.

Oh, yes. The engine got an oil change at the same time it got a new spark plug, and it’s definitely happy about all that. It’s out there right now, running like a brand new machine except for a slight howl–which is coming from the unit (generator) that produces the electricity, not the internal combustion engine.

Running a spark plug for that long before changing it is certainly not politically correct…but it’s definitely the way to get the most bang for your buck in the spark plug department.

4 thoughts on “Spark Plugs: How To Get the Most for Your Money

  1. We still change spark plugs on our car. One of these days we will get rich enough to have a car that is less than 10 years old. Until then, we just keep plugging along. Heeheeheehee

  2. Good one. WillStarr would be groaning.:)

    Both of our vehicles are over 10 years old–the Subaru’s a 2001, the GMC a 1996–but both have fuel injection. However, transportation is the one area where I do very much believe in changing plugs occasionally. If a generator dies until it gets a new plug, no big deal. We have spares on hand. A few minutes later, and the power is back on. But (obviously) if a car engine dies, the potential negative consequences are potentially much greater, so….

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