ac7ss's Forum Comments
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Some stations do temperature compensate, others do not.
The Ethanol does keep water out of the tanks, by absorbing it. (You end up paying for the water!)
There is a test to see how much Ethanol is in your fuel, It is mentioned in motorcycle manuals, and I cannot remember it at this time. (Something about how much water is absorbed by the fuel.)
posted by ac7ss July 22, 2010 at 11:57 PM
The trucks cannot control the temp of the fuel much, so it is closer to ambient, (depending on the time that the fuel sits in the truck this may not be much of a difference.)
Yes, the fuel is sold to the station by weight. but the addition of 4000 gallons of 75f fuel to a ground tank of 55f fuel will change the temp of the stored fuel. It is the change at the meter that works with or against you. (As little as it does, less than 1%.)
More people avoid 'Fresh' delivered fuel on the theory that it can stir up detrius in the tank. IMO this is filtered at the pump anyway.
posted by ac7ss July 20, 2010 at 2:05 AM
It looks like the error with fuel density is less than 1%, not really worth putting the fuel run on a separate trip.
posted by ac7ss July 17, 2010 at 4:09 PM
Using E-10 will drop your mileage by ~3.3% (125,000 btu/Gal vs 120,900 btu/Gal) based on just the energy content.
Your station attendant should be able to tell you the E content of the fuel.
If your station does not use temperature compensated meters, the colder the fuel, the more energy per gallon. (Ground temp is fairly stable, In the winter, fuel after the delivery truck dumps, in the summer, fuel before.) I am still trying to get a solid number on the real difference, but it is likely only in the 1-2% range. (Our ground tanks are about 57F here, so the most difference is 30F (15c))
posted by ac7ss July 17, 2010 at 3:56 PM
Another factor with the warmer weather, some stations finally get to reduce the "Winter Mix" of up to 10% ethanol.
You would be surprised at the difference in mileage between 5% and 10% Ethanol content. That is one reason that I don't fill in Seattle anymore if I can help it, they have more Eth in their fuel than we do in Olympia. (on average, ask your attendant.)
The counter effect is that it is more fun to drive in the warm weather. :)
posted by ac7ss July 17, 2010 at 3:32 PM