Thomas' Eclectric Oil. Uses Whereas many medicines are specifics, thai: Is, with a distinct effect in curing a particular disease, Thomas' Eclectric Oil is an all-purpose, internal and^ external family remedy for man and beast. However, to recommend a cure, the need for one 5 Dr. S.N. Thomas' Eclectric Oil was Canada's best selling proprietary medicine from the late 1800s through to the 1920s. The medicine lasted until at least the late 1960s. There are hundreds of variants, ranging from hand-made corkers to machine-made corkers to screw-tops.