Gasoline flash point -50*F
Methanol flash point +50*F
Motor oil flash point +450*F

The above numbers are approximations, but are in the ball park. This is a serious subject. The flash point is the lowest temperature at which vapors coming off a liquid can be ignited by an external ignition source. Most flying is conducted during the summer months when the ambient temperature is normally above 50*F. That being said, methanol (glow fuel) can also be a fire hazard during this period. Below 50*F methanol is no longer ignitable. I have flown for many years and have seen many crashes, but I've never seen a fire resulting from a gasoline or glow powered aircraft. I have however, seen fires coming from electric powered models. I fly glow, gas, and electric. The above figures may be helpful if again discussing your problem with the property owner.

EJJK