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  1. #11


    ok, thanks for the info

  2. #12
    Jr. Apprentice
    Join Date
    Jul 2013
    Weedsport NY


    The winter blend gas will make your mileage decrease. When you have the heat on, do you have it on the defrost setting ? Your A/C compressor cycles when using defrost, to help take moisture out of the cab. This would have the same effect as using the A/C. Also, if you run snow tires, they tend to be softer compound, for better grip this translates to more rolling resistance, which will effect mileage as well.
    The grave is not something that should be approached sedately in a well preserved body, but rather, slid into sideways, while yelling "Holy crap, what a ride !!!!!"

  3. #13


    thanks,nope no defroster on and no snow tires,just seems pretty weird.Winter= bad gas mileage

  4. #14
    Sr. Mechanic
    Join Date
    Jun 2011
    Tuscaloosa, AL


    I found this article on the gas mixtures about this time last year.

    Here's what I found on the mix gas

    Cars using summer-blend gasoline spew fewer harmful emissions and get slightly better fuel economy than those using winter-blend gas during the summer months.
    The difference between conventional summer- and winter-blend gasoline has to do with the Reid Vapor Pressure of the fuel. RVP relates to the volatility of a gasoline. The more volatile a gasoline, the more likely it will evaporate as the temperatures rises; evaporated gasoline contributes to unhealthy ozone and smog levels. Summer gasoline has a low RVP and is less likely to evaporate when compared to the high RVP winter grade. The Environmental Protection Agency says conventional summer-blend gasoline contains 1.7 percent more energy than winter-blend gas, which contributes to the summer blend’s slightly better gas mileage.
    The Energy Information Administration says the switch between the two fuels happens twice a year, once in the fall (winter blend) and again in the spring (summer blend). Summer-blend gasoline is typically more expensive to produce than the winter blend, and it won’t affect vehicle performance or the durability of the engine and fuel system, according to the EPA.
    In many large cities as well as California and New England, the EPA requires the use of reformulated summer- and winter-blend gasolines. These RFGs contain oxygenates that lower RVP and other toxic chemicals even further than conventional gasoline.
    2004 GMC Sierra SLT 6.0L 4x4
    UWS Low Profile toolbox 10% tint front and over stock back tint
    AirAid MIT and K&N airfilter
    BlackBear Performance

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