Fluctuion from hot to cold will not make any differance unless the temp drops below 51 degrees. If the bottle is tight there is no problem. If the fuel level has not dropped (or increased) you can be 98% sure there is no proplem.

The main problem with old fuel is that the methanol evaporates if not tight, or if you have a very small hole. It causes problems with idling, power etc. But wouldn't you expect the same if you adde oil till it was say over 40% ?