Beware of unsolicted advice concerning pouring moter oil against an exterior foundation of a building. This is not only unprooven, it poses a serious environmental hazzard. In truth most termiticdes are not as stable in most soils as termiticides which were manufactured prior to 1989. Chloronated hydrocarbon insecticdes (termiticdes) like chlordane, aldrin, lindane, etc. were known to have tremendous stability in soils with dissipation half-lives exceeding several years. However, the same qualities which made them good termiticides also made them environmentally unwise. Currently, there are approximately 12 termiticides registered for commercial use...most of these are pyrethroids like Demon TC, Torpedo (permethrin), Dragnet FT (permethrin, Biflex (lambda-cyhalothrin), etc... Organophosphates like Dursban TC (chlorpyrifos), or chloronicotinyls (Premise 75), or even newer chemistries like Termidor (Fipronil) or Phantom (chlorphenapyr) are also alternatives. In truth the physical and chemical nature of your soil surrounding your home can impact the effectiveness of the chemicals stability with respect to time. Soil clay content, pH, Organic matter content, particularly organic carbon content will greatly influence the rate of dissipation of an insecticide in soil. Temperature and rain will also play significant roles in this situation. I recommend you consult your local landgrant university extension entomologist or agronomist and evaluate your individal circumstances. Many will allow free or very inexpensive soil samples to be analyzed which can allow you to make a more informed choice. Baiting for termites, although generally more expensive, may be a better alternative. I am a university researcher working on the environmental fate of termiticides. I worked for a few years in the pest control industry before going back to graduate school. I have seen your situation time and time again, and unfortunately there are not always clear cut determinations to be made. However, the role of may university researchers like myself is to assist with problems like yours. I was searching for a related topic when I encountered your site, and felt compelled to drop a line... although unsolicited, I suggest you first consult with your local extension officer and go from there.