The stuff that evaporates out is the nitro, the nitro igniters, and the alcohol. If all that evaporated away, you'd be left with lube, right.

I got back into the hobby after 15-20 years. I had a shipping box of 4 gallons of RedMax. One of the bottles had leaked completely away. One was about halfway down. The other two were full to the top. After I'd used up the two good gallons (excellent fuel, that RedMax), I discovered that the closest LHS didn't have any fuel for sale with castor in it. So I bought a gallon of what they sold and did a little math. Blended in some of the old stuff with the new until I got down to the other LHS to buy some "fresh" fuel that had castor in it.

No way I'm throwing away perfectly good castor oil.