Mobil Medical

My father who just recently passed away was a field engineer for Mobil for 40 years. He built and tore down service stations and bulk plants. I guessing this sign came out of a bulk plant . It is hand painted, 5x7 in great shape. My dad had a large collection of Mobil stuff that he salvaged when they tore things down. He donated most of it to a Mobile museum but I found this as well as a 1941 oil chart when I was cleaning out his office. I was wondering if anybody knows anything more about it?