Stable cool temp is like 60-65' and doesn't vary at all. Yuo have the cool part but not the stable part. This causes the fuel jugs to breath if they aren't well sealed eventually causing contamination from humidity. Though unless you are in a real humid area it probably would take some time. Your fuel in the jug is probably ok. The engine in the plane though breathes easily and any leftover fuel in the engine will collect humidity out of the atmosphere quite quickly. Methanol is 'hygroscopic' meaning it attracts? moisture. []