Diesel Guard Audible Warning System Review

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Product Requirements:
A vehicle that uses diesel fuel

Here in West Texas where there are so many ranchers and farmers, diesel
trucks are de rigueur. Whether it be a
Chevy or
Dodge, people swear
by the pulling performance of their
, Duramax

engines. Even though you will never get a group of old-timers
to agree on which diesel motor is best, they will all concur that next to water,
gasoline is a diesel engine owners’ worst nightmare.

Why? Because diesel and gasoline engines are two entirely different breeds.

In a nutshell, A gasoline engine operates on combustion, whereby
either a carburetor or a fuel injector will introduce a tiny spray of gas into
the chamber to be mixed with air. As the piston rises to compress the mixture,
the spark plug sparks and the mixture is ignited, causing it to explode, or
combust. This drives the piston back down and turns the crankshaft. The exhaust
is released, and the process is repeated over and over, multiplied by however
many cylinders the vehicle has. A diesel engine, on the other hand operates on
compression. Air is accepted into the cylinder and then the diesel fuel
is directly injected. Instead of a spark, the heat from the compressed air will
ignite the fuel, which drives the piston and completes the process. The higher
compression ratio of a diesel engine actually allows it to use fuel more
efficiently and get a better miles per gallon than a similar cylindered gasoline
engine would rate.

As you can imagine, the two different processes are possible because the
fuels themselves are quite different. Whereas gasoline is a highly
refined product, diesel is a much oilier, heavier and less refined result of the
distillation process. As a result, diesel is also quite lubricating for the
parts of the engine with which it comes into contact. Gasoline, on the other
hand evaporates quickly and does not have the inherent lubricating properties.

When a small amount of gasoline is introduced into a diesel engine, it
probably won’t make a huge difference on performance. In fact, I have
heard of people in cold climates adding small amounts of gas to their diesel
vehicles that were not equipped with glow plugs. Supposedly it helps them start
better, however I have never attempted it and probably wouldn’t. Once gas has
been introduced to a diesel engine, if the vehicle continues to run smoothly and
without "knocking" or dying, then the worst that may have occurred is premature
wear on the fuel system and cylinder.  However, if a diesel tank is filled
with gasoline, and there is not enough diesel left to dilute the gas and
lubricate the engine, then the engine will run poorly if at all. The injectors
and the injector pump will may even need to be replaced.

The only real remedy when the mistake is made, is to immediately flush the
gasoline from the system and refill with straight diesel. In these days of
skyrocketing fuel and vehicle service prices, gasoline in a diesel engine can be
a costly mistake.

If you are a diesel owner, then you are used to looking for the familiar
green handle and the attached water filter at the diesel pump. However, if you
were to loan your truck to someone that usually drives a gasoline engine, then
there is always the chance that if they go fill up, they may forget.

With that scenario in mind, I would like to introduce our readers to a clever
new item that I recently received from the UK, a land where diesel engines are
commonly found in many passenger vehicles as well as commercial. The product is
the Diesel Guard, a light activated
voice reminder box that is made to be mounted inside the fuel door on a diesel


The Diesel Guard is composed of two pieces of black plastic that have been
fitted together. It measures approximately 3" long by 1.75" tall x 0.5" thick.
The front consists of just the light sensitive chip and the speaker, there are
no other buttons or user settings.

Because it is meant to be used in an incredibly filthy environment, the
Diesel Guard is "hermetically sealed", therefore, the battery is not user
replaceable. The built-in dry cell battery is estimated to last for
approximately 750 reminders, and the life of the unit itself is estimated to be
about two years – most likely because of the dirty environment in which it will
be put to use. There is a one year no-quibble guarantee, so if your unit is
faulty you’ll be protected.

It can fit just about anywhere inside a fuel lid, as there is usually a bit
of room inside the compartment. A thick piece of double sided tape is attached
to the back of the Diesel Guard, which allows it to be easily affixed to the
flat interior of the vehicle’s fuel door.

When the fuel door is opened, a small, light sensitive chip on the Diesel
Guard is activated. Much harder to miss than the standard "Diesel Fuel Only"
sticker found on the fuel door or the "Diesel Fuel Only" notice on the
dashboard, the Diesel Guard emits a loud
audible reminder
the minute the fuel door is opened, saying "(four beeps) This vehicle runs on
diesel fuel,  insert diesel fuel only, (three beeps) insert diesel fuel
only, (three beeps) insert diesel fuel only, commence filling diesel fuel only!
You had better believe that even the most absent-minded idiot would not confuse
the type of fuel needed after hearing this warning!

In case I didn’t make myself clear, the Diesel Guard is loud, but it needs to
be considering how noisy it can be at the pump. For someone that isn’t worried
about making a fueling mistake – it might be a little bit embarrassing to hear
the nagging voice every time the fuel door lid is opened. However, the nagging
reminder is a small price to pay for peace of mind if you are in a family that
has both diesel and gasoline vehicles. The upside is that the reminder only
cycles one, turning itself off after the above speech is made. Unless the fuel
door is shut and then reopened, causing the switch to trip, no further
mortification will be necessary.

Honestly, I can’t imagine why every truck rental place in the United States
does not have these installed on their entire fleet. In fact, I think that the
Diesel Guard is something that every dealership in my town should include
standard with their diesel pickups. I heartily recommend this product to
anyone with a Diesel vehicle; the peace of mind alone is worth the purchase

The Diesel Guard Audible Warning System may be purchased
here and

Price: Approx $29 (£14.90)
Contact John for bulk or fleet

It’s loud – you’ll be able to hear it at the pump
No more gas in a diesel engine mishaps
Easy to apply, requiring no special tools

It’s loud – you may get embarrassed at the pump ;0)


Product Information

Manufacturer:Diesel Guard
Posted in: Miscellaneous
{ 1 comment… add one }
  • John Daly May 8, 2010, 8:41 am

    I brought this device, but it is too embarassing! Everybody looks at you and you just feel like sinking into the ground to stop the eyes staring at you! Not worth it!

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