Interesting. I spent some time trying to track this down.
Oilzum has been around as a product for well over a century. The design of the central logo seems to be pre WWI.

Here is all of the lettering that encircles the logo.

I am have not determined when the lettering was added to the logo to make the Oilzum sign, other than it was some time in the first half of the 20th century.
The style is thick and thin sans, developed from the 1890s onward in fonts such as Taylor Gothic, Studley and Globe Gothic. It is found in only a few American typefaces from the 20th century.
I checked my file collection and did not find a match.
Pending a check of McGrew's American Metal Typefaces, I suggest that this is well executed hand lettering with the flavor of the three mentioned fonts.
Don