NORWALK - As winter approaches and oil prices remain high, some homeowners may consider heating their homes this year with natural gas instead of oil. At first glance, natural gas seems to have a greater advantage over oil. Not only is 90 percent of natural gas from North America, but the cost of natural gas is far less than oil. Oil prices are still hovering at just under $4 a gallon, while natural gas costs $1.32 per cubic foot. Oil companies, however, are warning customers to think carefully before switching to natural gas. They claim that converting a home from oil to gas can cost homeowners between $4,000-$10,000 in equipment alone. Additionally, with oil prices in a constant state of flux, it?s unclear if and when a costly switch will pay off in the future.