My UDS started life as a container for motor oil. been using it for several years, and haven't had a single issue. I did 2 or 3 HOT burnouts before assembly. She's so coated with grease now, it's all good.
I'm of the opinion, if you're uncomfortable with the barrels previous use, don't use it.
22.5 OTS(H), 22.5 OTG(DA), 22.5 Daisy Wheel Kettle(EE), NBBD, UDS, MUDS, 6-burner gasser