Friday, September 22, 2023


RVelectricity: Can cow magnets help improve your mileage?

Dear Readers,
The rising cost of gasoline and diesel fuel is causing a lot of “free energy” and “mileage boosting” scams to be posted everywhere. Here are a few of my favorites from the past as well as brand-new scams for the computer age.

Everything old is new again…

I remember seeing ads for Cow Magnets in the back of Popular Mechanics magazines back in the early ’70s. The idea is that by clamping a pair of heavy-duty magnets around your fuel line close to the carburetor it would somehow align the ions in the gasoline and extract more energy when it was burned. Actually, every farm kid knows that cow magnets are a real thing that dairy farmers get cows to swallow, which stops bits of barbed wire and nails that might get into their feed from traveling though their digestive tract.

Cow magnets for better mileage are 100% Bull!

There is ZERO proof that Cow Magnets do anything at all to improve your gas mileage. Yes, modern vehicles don’t have a carburetor any more. Instead they have some sort of fuel injection under computer control, and many also have something called GDI (Gasoline Direct Injection) which creates a timed spray of gasoline into each cylinder, sort of like a low-pressure diesel engine with spark plug ignition. Add in a turbocharger and you’re now extracting near the theoretical limit of energy in every gallon of gasoline or diesel.

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Magic spark plugs are a complete fizzle

Here’s another one that was a big deal in the ’70s and ’80s and has shown up on a number of my latest news feeds. The idea is that there’s some special spark plug design with unobtainium contacts that can somehow provide better ignition of the fuel/air mixture. Now, back in the day of leaded gasoline you needed to change your spark plugs every 10,000 miles or gas mileage would suffer.

So if you put in a bit of magic zirconium-tipped spark plugs to replace your dirty factory/OEM plugs, of course your mileage would increase a little bit. But that would be true if you simply cleaned and re-gapped your dirty spark plugs. However, in the current days of electronic ignition and unleaded gasoline, spark plugs last 50,000 miles or more and there’s no points and condensers to change. Actually, the computer in your car tunes your engine 100 times every second, so there’s nothing you can do to improve its performance. So replace your spark plugs with quality plugs recommended at the mileage intervals suggested by your vehicle manufacturer, and that’s as good as it’s gonna get.

Free energy generators are just smoke and mirrors

I see these so-called free energy videos all the time, where someone builds a strange looking gadget from an old car alternator or a few bearings and spark plugs with magnets. Once you spin it up, the light bulb magically lights up and the claim is now you can have free energy forever.

But the reason for these scams is the number of views that these YouTube videos get in a few days, sometimes in the millions. Of course, there’s a battery cleverly concealed somewhere in this free energy scam, or maybe they’ve added a magnetic coil feed by AC power under the table, sort of like your wireless phone charger. That’s how I would do it if I wanted to make a free energy scam.

If wishes were horses, all beggars would ride…

Note that I really did try to build a Perpetual Motion / Free Energy generator out of an electric motor and car generator when I was 8 years old. It didn’t work, but I did manage to blow the fuses in my parents’ electric box. It didn’t work 60 years ago when I tried it, and it certainly won’t work now, no matter how much you wish it would. The lesson is that no matter how badly you wish for something to work, any gadget that appears to break the laws of physics as we understand it is complete bunk.

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And finally, the OBD2 tuner scam

All modern vehicles have an OBD2 port under the dash, which does allow you to add something like a Bully Tuner to your diesel truck. While those tuners can allow you to increase your horsepower (voiding the warranty and possibly wrecking your engine), there’s no proof that any of these tuners can improve fuel mileage. But the real scams are the ones that have nothing but an LED light inside with no computer interface at all. When you plug them in, a magic glow assures you that they’re doing something, but in reality they’re nothing more than a night light for your feet. So don’t fall prey to this scam.

What does work?

The only thing that always works won’t cost you a dime. So how about slowing down to the speed limit. That’s right, if the posted speed limit is 65 mph, then don’t drive at 75 or 80 mph.

Simply driving at the posted limit will probably improve your gas or diesel mileage by 10% to 20% compared to going 10 to 15 mph over the limit. Yes, it will take you longer to get there, but what’s your hurry when you’re camping?

Let’s play safe out there….

Send your questions to me at my new RVelectricity forum here.

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.




    • Was that the one that had vanes in a plate you mounted under the carburetor that would swirl the fuel/air mixture like a tiny tornado? If so, then I remember it distinctly.

  1. I do recommend the using of the magnets in your diesel trucks. But do not claim any claims of improving mileage.
    I use them in my truck fuel tanks much like a magnet in a differential.
    I put them in the tank in order to attract metal contaminants that can and does come with the fuel we buy on occasion.

  2. In the 70’s energy crises there were two others that I recall. One was the distribution (selling) of plans for the Pogue carburetor which would achieve 50 MPG. The Pogue carburetor was invented in the 30’s and reintroduced in the 70’s. It scammed again.
    The other device was a screen and gasket set that was to be installed at the base of the carburetor to “mist” the gasoline before entering the cylinders.
    I like the new inventions. Just plug into the OBD port. Very easy, cheap and you get the same results.

  3. I too remember the cow magnet quest. As a retired farmer was always getting asked where can I buy these cow magnet things. It always was good for a laugh.

  4. There’s a sucker born every minute. The fact that new “miracle” fuel saving devices appear, and old ones reappear, proves it.

  5. Mike,

    You missed the “Magna-spark that plugged into the top of the distributor (back in the days of distributors) and on demonstration increased the RPMs and therefore the power and gas mileage…big in the 1960s. The scammer had a way to increase the engine speed when he installed the “Magna-spark.


  6. I guess no one remembers the 70’s and gas rationing and reduced speed limits. I’m in the Phoenix area. I 10 is 70 mph. BIG JOKE. Do 85/90 or get run over. Every traffic light is a Christmas tree light at the dragway. I guess they can’t see far enough ahead to see the next light just change to red. The difference today from then is no lines at the pumps. Got the gas, now PAY for it

  7. Ha! I sometimes listen to old episodes of Car Talk (Click and Clack) – recently had a call in and some fun on this very subject.

    • That’s exactly what inspired me to write this article. I loved Click and Clack and still listen to their “Best Of” episodes.

  8. I remember the cow magnets misinformation as it was if you were to do it it tends to cause a more serious issue because it holds metal particles it tended to clog the fuel line and if and when you removed them that slug of metal particles would just go down the line and plug up things further down.

  9. My best mileage tip? I pull my 35′ 5th wheel at 55 mph MAX. I average 12.5 mpg, while pulling at 65 gets me 10 mpg. At 5 bucks a gallon it is a no brainer, and the extra speed just beats up the trailer more. Slow down folks, just slowwww dowwwnnnn.

  10. If these magic devices actually worked don’t you think that the manufacturers would install them to improve their corporate fuel mileage averages

    • You are 100% correct. If you invented anything that could increase MPG by even 10% you could sell the patent to the automobile industry for hundreds of millions of dollars, perhaps more.


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