The full name is the Independent Oilmen of America. Do a google search and you'll come up with a few hits:http://www.american-automobiles.com/James.html
I know Standard Oil sued them over the Red Hat logo. They apparantly said it was too close to the Red Crown logo they had, and it would confuse consumers!!
For anyone who wants obscure information, WH Barber, of Fyre Drop fame, was president of the IOMA in the 20's.