Marvel Mystery Oil, still around since 1923

Why did he give it the name Mystery Oil? Is it said that Burt Pierce refused to divulge the formula for his new product and, when asked about its ingredients; he would say “It’s a Mystery”, and the name caught on The Marvel Oil Company was founded in 1923 by Burt Pierce, inventor of the Marvel Carburetor. His carburetor was standard equipment on eighty percent of all vehicles produced after World War I.

I bought the above for 10 dollars at a swap meet

I found the above in a VW Bug https://justacarguy.blogspot.com/2012/03/judson-supercharged-vw-bug-even-has-two.html

And I found this in a racing Oldsmobile https://justacarguy.blogspot.com/2018/05/gregorys-speed-shop-oldsmobile.html

You can find more information on Marvel Mystery Oil and it application here: http://www.marvelmysteryoil.com/