DX in ham terms stands for anyone outside of the calling stations country, what else has DX stood for…
A. A famous stop on route 66
B. A famous truckstop in Iowa
C. A lubricant company
D. A Canadian made Semi Truck
Answer is C… In 1925 Sunray Oil Co. purchased six service stations from the Diamond Petroleum Co. , with this purchase they acquired the diamond shaped symbol and the company’s major line of products known as Diamond Products. In 1932 scientists at the laboratories in Tulsa developed & patented an upper-cylinder lubricant for use in the co.’s gasoline. The brand name “D-X” was first used in 1933 when the co. announced “D-X Lubricating Motor Fuel. The “D” was for “Diamond” , the “X” was used to represent the secret lubricating factor of the gas. Sunray was founded by Mr. Son & Mr. Ray in 1920…..
Source for the Rest of the story and more info…. Flickr