What's the difference between winter and summer fuel?

Yes, the refiners still blend fuel in the winter depending on it's destination market. I don't remember if that happens at the refinery or at the pipeline terminals.

 

Winter blended fuel has more additives to help with no gelling in cold weather. It will definitely affect fuel economy. Usually during the winter months running winter blended fuel and running in denser cold air, I usually lose at least 1 to 1.5 mpg.

 

# 2 fuel will gel at 14 degrees.You will probably see winter blend decals on the fuel pumps in the Northern parts of the country.Canada and Alaska you will see #1 diesel,probably good to -40.

#2 fuel will start to get cloudy below freezing temps and stop flowing at 14 degrees.
#1 will flow to -40 degrees.

 

#1 also tends to desolve 1 micron filters. When i run number 1 in my 579 the filters start to break down after 5k miles or so at most.

 

I can't speak to the specifics on diesel, but I know that winter blend gasoline is allowed to have a higher Reid vapor pressure. They blend butane into it.

 

If you run in canada, they switch all diesel to number 1. FYI.

 

In both cases it boils down to the same thing, the average length of the carbon chains is shorter in the winter blends, reducing density and BTU/Gal as well as increasing volatility. It also lowers the pour point of the diesel.

 

-43°C was the coldest I've seen and diesel wasn't even coudy.

 

#1 diesel is the same as kerosene and jet fuel.

#2 diesel is a thicker oil, it is pretty much the same as Home Heating Oil.

They blend #1 and #2 for the winter.