Your last point is key. The furnace you have now can’t offer many more years of service, and even if it did, you can be sure that a new, high efficiency model will save you money in the long run because of its design. There are substantial efficiency gains available with all new furnaces these days, especially the direct-vent gas models that don’t need a chimney. We live in a world where energy prices are volatile and will stay that way. Natural gas prices could skyrocket in the short term, just as oil prices could. But in the long run, given the furnace technologies available right now, a new natural gas furnace remains an excellent choice. Insurance companies everywhere are exercising more control over residential oil storage equipment because of the major hazards and expenses posed by oil leaks. There’s good reason for the higher level of caution.