Found a coin of sorts. How do I find out what it is?

Question

Bronze in color round in shapeACTOL S.A.E.30 is stamped on one side nothing on the other side a hole punched in the top of circle

Answer 1

You do indeed have a metal marker related to oil, in this case, a synthetic lubricant similar to oil. ACTOL refers to Actol Chemicals, Ltd., a company that also makes adhesives, located in Montreal, Quebec, Canada. The company, founded in 1954, still exists. Here is their web site:
http://www.actolchemicals.com/

SAE 30 refers to the viscosity of the lubricant, in other words, the ability of the liquid to flow. (In everyday living you will find this term associated with motor oil.) SAE 30 oil flows more freely than SAE 40.

Interesting item!

Answer 2

Sounds like a metal label that tells the brand and the the type of oil in a 55 gal drum of oil. The hole is so the label can be wired to a container.