shop-talk supported in part by Fat Chance Garage
http://fatchancegarage.com
On 11/16/05, Randall <tr3driver@comcast.net> wrote:
>
>
> shop-talk supported in part by Fat Chance Garage
> http://fatchancegarage.com
>
> > Just reading an Advance Auto Parts advertisement. There is a heading
> > "Advance Know-How, Creative ways to get ready in Advance and save
> > gas!" It says, "Buy gasoline during the coolest time of the day--
> > early morning or late evening is best. During these times gasoline
> > is densest." Anybody think that will "save" any more gas than a
> > tornado thing? :-)
>
> It's an old myth, I first heard it when I was learning to drive in the early
> 70's and it was old even then. Never could tell that it made any difference
> whatsoever then, and I'm sure that modern pumps are temperature compensated.
> Even if not, the difference would likely be too tiny to measure.
>
In the US, it's almost universal to sell retail fuel from
uncompenstated pumps. Fuel is only temperature corrected where it's
required, or where there's an advantage to do so. Up to the point
that fuel is dispensed, at the refiner and the jobber, it's measured
in gallons at 60F. If the temperature of the fuel is above 60F, the
dealer is making an excess profit. If it's below, the customer is
paying less. Gasoline density changes by about 1% per 10 degrees F
from 60F.
I suppose there may be states in the US that require compenstated
pumps, but most don't. In many, they might even be illegal, since the
certification isn't temperature compensated. Around here, they use a
special gasoline can. It holds five gallons. It narrows greatly at
the point where the level is measured. There's a sight glass, there.
If the level is between two marks, it's acceptable. (Actually, as
long as it's above the minnium, it's okay. You're allowed to
shortchange yourself, if you want.) They do two tests, one at fast
flow, one at slow. I think the requirement is+/- 1%, but I'm not
sure. There's a picture of the sort of thing used here:
http://cv1.collatech.com/sites/conceptcom/CyberVendor.dll/viewproduct?&Action=Update&UT=OldUser&SN=N/A&HTMLFILENAME=&productno=5380121724
They're really carefull with the things.
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