Oh, I get it. Sorry, I didn't catch on with the terms "light" and "heavy".

I'm not sure that methanol burns "too quickly" or that isopropanol burns "not so well". It's a bit more complicated than that. In this situation, it has more to do with vapor pressures at a given temperature. BEFORE EVERYONE'S EYES GLAZE OVER, I won't bore you with the detail, but suffice it to say that in hot weather, methanol can boil so vigorously that you lose efficiency ("excessive" thermal feedback). In cooler weather, methanol is great.

Isopropanol actually puts out plenty of heat and doesn't have any trouble staying lit or anything like that. It's just that isopropanol doesn't burn cleanly.

The idea of mixing the two for hot weather (to avoid excessive thermal feedback in the methanol) has some merit, but I don't know how it would work. The isopropanol has a very high heat content and might just exacerbate the excessive thermal feedback. I haven't tried it.

Some people will mix just plain old water with their methanol to retard excessive thermal feedback. I'd say water is the way to go until we get some experiments done.

HJ