Date:         Thu, 10 Mar 2011 09:13:59 -0600
Reply-To:     mcneely4@COX.NET
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dave Mcneely <mcneely4@COX.NET>
Subject:      Re: Gas Saving Tips
Comments: To: John Rodgers <inua@CHARTER.NET>
In-Reply-To:  <4D78DF44.1040000@charter.net>
Content-Type: text/plain; charset=utf-8

---- John Rodgers <inua@CHARTER.NET> wrote:
>   This came from a friend's friend in CA. Dunno the efficacy of it but
> seems reasonable.  Hope it helps us all.
>
> John
> *****************
>
>      TIPS ON PUMPING GAS

>      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.

While the temperature/specific gravity relationship is well founded, and so buying hotter gasoline would yield less actual fuel than buying cooler gasoline, I am not sure there is any efficacy in time of day of fill up, unless the storage tanks are above ground.  The ground temperature actually changes rather slowly with air temperature, and measurements a foot below ground show only very slight temperature change over the course of a day.  Most storage tanks are considerably deeper than that.  If gasoline were metered by weight, we would get the same measure every time (ie. a kilogram is a kilogram is a kilogram, except for variation due to distance from the center of the earth).  Now, we do get more fuel per gallon in late winter than we do in late summer.

As for the other recommendations, judge them for yourself.

mcneely