What's the Best Gas for Cold Weather?

OK, I need some gas for some cold weather trips. So, I bopped into REI.

Hey, wait a minute. This gas is 75% butane and that one is 65% isobutane and this one over here is three  gasses. What the heck??

How is anybody supposed to know which one is gonna work for cold weather? And what the dickens are these blends all about anyway?   All important questions if you're headed out in cold weather. I try to answer them all in two posts on my blog:

What's the Best Gas for Cold Weather?

Why blended gas? Why not just use propane?

HJ