With the price of gas these days (over $3.00 per gallon at the time of this writing), most people
are feeling the economic pressure and are wondering what they can do to lower their gas costs. This article introduces one of several ways to get as many miles per dollar as possible.
When it comes to the grade of gasoline or octane you put in your car, “more is better,” right?
Not always. There are a number of myths surrounding the use of high octane gasoline.
Myth #1: Using high-octane gasoline will make my car run better.
Not quite. If your car is “pinging” or “bumping”, a higher octane gas will help or eliminate the pinging and save your engine, but it doesn’t add power directly. However, it prevents its electronic ignition from delaying time as an “anti-knock” measure when a ping is detected.
Myth #2: My car will get more miles per gallon if it uses a higher octane gas.
Since a higher octane gasoline does not produce more power, you will not get better gas mileage.
Myth #3: My engine will run cleaner and produce less emissions and smog with a higher octane gas.
Is not true. Many oil company advertising methods might lead you to believe this, but octane rating has nothing to do with how “clean” your engine runs.
Myth #4 – Octane is added to gasoline to produce a higher quality fuel.
No, actually Octane it is gasoline, at least most of it. See octane rating below.
You can save money on gas simply by using the lowest octane gas your car will tolerate. Use a higher octane
what the manufacturer says gas is simply a waste of money. If you are not sure what octane your car is designed for
use, you can start with the lowest octane (87 in most areas) and give it a try. If it pings under load, then go up to the
following octane and only buy the lowest octane grade your car needs. To learn more about octane rating, keep reading.
What is “Pinging” or “Knocking”?
Most of us have heard the rattle under the hood, usually when the engine is under additional load like
climb a hill, tow a boat or in a loaded truck. The noise itself is caused when the air-fuel mixture in the
the compression chamber ignites too early (pre-ignition or detonation). This condition causes the fuel-air mixture to burn unevenly and
produces the ping or knock sound. This uneven combustion causes flash points in the combustion chamber and can lead to engine damage.
What does octane do?
Without going into all the chemical properties and technical aspects, basically, the octane rating raises the
combustion point of gasoline when it is under compression and retards combustion. The result is that it does
less volatile gasoline so it doesn’t ignite before its ignition system causes it to fire at the right time.
The intent of the octane rating is simply to provide an anti-knock property.
The octane number you see at the pump is simply a percentage of the chemical octane number in the
gasoline blend In other words, if you buy gasoline with an octane rating of 87, that blend contains 87% octane and
the rest are lower quality chemicals like heptane. See also http://en.wikipedia.org/wiki/Octane_rating
What about the “Octane Boost” additives?
If your car requires a higher octane gasoline, you can use “octane boosters” available at your local auto parts store. The cost
and effectiveness will vary. Test a full tank with an additive to see if your can is working properly, then do the math to see
if that makes sense. Here is a cost analysis for my 1993 Mustang GT:
Example: 1 bottle of additive to boost a tank of gas costs about $5.00. With a 15-gallon tank, this adds about $.33 to the cost of each gallon of gas, plus the hassle of going to the auto parts store to buy it and remembering to add it at every fill-up.
If you really want or need a high octane mix, you may want to make your own.
homemade octane booster
There are a number of websites and blogs that post recipes or “homebrew”. I’m not going to post it here as I can’t directly endorse the
use or safety of doing it yourself. However, if you’re looking for a recipe to increase octane with xylene or toluene, you’ll find it there. The chemists
xylene and toluene are of a higher “quality” and can produce an increase of more than 100%. The chemical octane by itself, by definition, can never produce more than one
octane above 100.
Other ping solutions
If your car continues to ping or knock even though you are using an octane rating of gasoline equal to or higher than that specified by your car manufacturer, this
it is an indication of engine problems that you should consult with your mechanic. There is a well known problem that you may be able to
try to diagnose yourself and that is the case for a stuck or faulty EGR valve. It is beyond the scope of this article to explain how to check
your EGR valve, but it’s something to look into if your car has a chronic pinging problem.