Using Critical Thinking to Debunk Urban Legends

There are so many reasons I’m thankful for social media, and the reduced number of chain/scam/urban legend emails I get is a big reason.

Have you received this email?

TIPS ON PUMPING GAS

> > I don’t know what you are paying for gasoline, but here in
> > California we are paying up to $3.75 to $4.10 per gallon. My
> > line of work is in petroleum for about 31 years now, so here
> > are some tricks to get more of your money’s worth for every gallon:
> >
> >  Here at the Kinder Morgan Pipeline where I work in San Jose
> > , CA we deliver about 4 million gallons in a 24-hour period
> > thru the pipeline.. One day is diesel the next day is jet
> > fuel, and gasoline, regular and premium grades. We have
> > 34-storage tanks here with a total capacity of 16,800,000 gallons.
> >
> >  Only buy or fill up your car or truck in the early morning
> > when the ground temperature is still cold. Remember that all
> > service stations have their storage tanks buried below
> > ground. The colder the ground the more dense the gasoline,
> > when it gets warmer gasoline expands, so buying in the
> > afternoon or in the evening….your gallon is not exactly a
> > gallon. In the petroleum business, the specific gravity and
> > the temperature of the gasoline, diesel and jet fuel, ethanol
> > and other petroleum products plays an important role. A
> > 1-degree rise in temperature is a big deal for this business.
> > But the service stations do not have temperature compensation
> > at the pumps.
> >
> >  When you’re filling up do not squeeze the trigger of the
> > nozzle to a fast mode If you look you will see that the
> > trigger has three (3) stages: low, middle, and high. You
> > should be pumping on low mode, thereby minimizing the vapors
> > that are created while you are pumping. All hoses at the pump
> > have a vapor return. If you are pumping on the fast rate,
> > some of the liquid that goes to your tank becomes vapor.
> > Those vapors are being sucked up and back into the
> > underground storage tank so you’re getting less worth for
>> your money.
> >
> >  One of the most important tips is to fill up when your gas
> > tank is HALF FULL. The reason for this is the more gas you
> > have in your tank the less air occupying its empty space.
> > Gasoline evaporates faster than you can imagine. Gasoline
> > storage tanks have an internal floating roof. This roof
> > serves as zero clearance between the gas and the atmosphere,
> > so it minimizes the evaporation. Unlike service stations,
> > here where I work, every truck that we load is temperature
> > compensated so that every gallon is actually the exact amount.
> >
> >  Another reminder, if there is a gasoline truck pumping into
> > the storage tanks when you stop to buy gas, DO NOT fill up;
> > most likely the gasoline is being stirred up as the gas is
> > being delivered, and you might pick up some of the dirt that
> > normally settles on the bottom.
> >
> > To have an impact, we need to reach literally millions of gas
> > buyers. It’s really simple to do.  Again, all you have to do
> > is send this to 10 people. If those 10 send it to ten, who
> > forward it to ten, then the math becomes a pyramid.

Urban Legend emails like these float around and are forwarded so quickly that it’s clear we are not using critical thinking to evaluate the information.  The emails usually begin with the author implying knowledge about the topic.  In this email, the author claims credibility by saying he/she works for the Kinder Morgan Pipeline.  Be suspicious when they email starts with a claim of credibility rather than explaining the science behind the claims.

Next, do your homework.  A quick Google search of “gas pumping tips email” reveals tons of results confirming that the contents of the email are either mostly false or the effects are overstated.  Use the resources available to you to check the facts.

Let’s think critically about the section that advises you to pump your gas slowly.  The argument is that when you pump your gas quickly, you are stirring up the gas tank and causing vapors.  Those vapors are then sucked back into the underground gas tank due to the vapor return hose.

There are many assumptions in this argument.

1)  More vapors are created when pumping gas on the highest setting than the lowest setting.

2)  The amount of vapors created while pumping a tank of gas is costly enough to cause concern.

3)  The amount of money lost due to vapors is more than the amount saved by pumping more quickly and moving on with your day.

Here’s a critical thinking challenge for the weekend:

Assuming I pay $3.39/gallon to fill up my 12.7 gallon gas tank, how much would I save by pumping on the slowest setting versus the fastest?

Editor’s Note: Breanne Harris is the Solutions Architect for Pearson TalentLens.  She works with customers to design selection and development plans that incorporate critical thinking assessments and training.  She has a Master’s degree in Organizational Psychology and has experience in recruiting, training, and HR consulting.  She is the chief blogger for Critical Thinkers and occasionally posts at ThinkWatson.  Connect with her on LinkedIn and Twitter for more of her thoughts.