Winter Gasoline Vs Summer Gasoline

[tswirka]

I asked one of the blending chemists at work what the difference is, I work at a refinery and he dirrects the operations dept. what gas to blend. He said the vapor pressure was related to the temperature at which gas will release vapors. they control the blending of different grades of gas, which in turn determines the performance in the engine. in the winter you need more vapor to run the engine, in warm weather the gas will create vapors itself.
He said if the refinery already switched to one or the other and you had to switch back for only 15,000 gallons, you got a **** of a deal! 15,000 gals. is only 357 barrels (42 gals ea.) and we run 90,000 barrels a day of crude. the economics of stopping production to make something else is figured into the price of what she bought.
just thought youd like to hear that.
Todd

 

[Egon]

Winter gas just may have a little more butane in it.

Egon

 

[RalphVa]

Summer gas has a LOWER vapor pressure due to use of less butane in it, because less is needed to start engines in the summer. Think they use a test called Reid Vapor Pressure to measure it.

Ralph