On Sat, 19 Dec 2015 17:04:34 -0700, Tony Hwang wrote:

We used to fill winter grade on our camping trailer to use in winter
time. I heard it is mixed with Butane to keep it from freezing. Well
there is winter grade gasoline too.

I don't know if there /is/ a winter-grade propane, but gasoline is
generally comprised of at least a hundred different chemicals, which,
compared to something as simple as propane, isn't at all the same thing.