How long does it take to do the switch to summer blends during this long winter?
Keep in mind, the summer blend is made with more expensive components. I’ll try to find something about the switch over itself. Often this time is used to do other work as well while the units are down. Which means the down time is greater than required for just the switch.
So what’s the difference between summer and winter blends? Well, it’s important to note that butane (4 carbons) is relatively cheap. Molecules with more carbon atoms are more valuable since it’s easier to break molecules down than build them up. Which means that refineries looking to make the most money want gasoline blends that have the most shorter chain molecules while still having a mixture that is stable enough not to evaporate during the distribution process. It’s also important to note that butane has less energy by volume than longer chain hydrocarbons.
In the summer, it’s warm out. Which is nice for swimming, but bad for living in a world where we have tanks of hydrocarbons all over; zipping around us, stored in our garage, buried at gas stations, airports, and vehicle fleet facilities, etc. When it’s warm, things evaporate easier, and shorter molecules evaporate easier than larger molecules (they are more “volatile”). Reducing the volatility of gas cuts evaporative emissions, which contribute to ground level ozone and related environmental and health problems. So regulations were put in place to protect us and dictate that summer blend gasoline have to effectively be heavier (less volatile, more longer chain molecules).
In winter, it’s cold, and so refineries are allowed to produce gasoline that evaporates more easily. So they maximize the cheap, low energy butane in the mix. Any benefit of your car starting more readily is really limited to old and/or poorly maintained vehicles. Current vehicle technology is pretty hardy.
What’s the result? Well, basically, winter blend gasoline has a larger percentage of butane in it. And since butane is cheaper and has less energy, winter blend thus costs less and gives us a lower MPG when we burn it. So it’s a wash, right? Eh, maybe. Your vehicle miles per gallon typically will drop 2-8% when you start filling up with winter blend. Unfortunately, evidence suggests that the common price decline is 2-4%.
https://itisscience.wordpress.com/2011/11/28/winter-gasoline-yes-there-is-a-difference/