What color is it ? The reason you shouldn't use it is normally gas is a red can blue or yellow is for diesel somebody can mistakenly think is has gas , water, diesel , kerosene etc and potentially injure themselves or others . To answer your question it can be used from diesel to gas but NEVER gas to diesel . The gasoline fumes will ignite in the diesel device causing injury / death. Make sure to clean it out well before (if) you switch