The caduceus is often associated with the god Mercury, and Sunoco marketed its motor oil as "Mercury-Made" in the 1940s, due to the use of mercury in its process at that time. Although the association with Mercury seems to have disappeared by the 1950s, some stations still had the caduceus. My grandfather's station, built in 1957, had one over the "SUNOCO" letters on the station front. I believe that the top of the torch had a red lens that actually had a light inside. These signs seem to be rather rare. I saw one on ebay 2 or 3 years ago that sold for several hundred $$. Good luck in your search.
