My barrel didn't have a spray on liner. I bought it new.
It was sprayed with some kind of rust preventative, so I filled it with pallet wood and fired it up. Burned hot and clean.
I cleaned the inside when it cooled, built the UDS that day.
I sprayed the insides with Olive Oil...
Dark thirty I filled the basket with Lump charcoal and fired it up.
I let it burn at 250° for about an hour then made up two 'Fatties' and tossed them inside to smoke.
A couple of hours later I had two 'Fatties' and the insides of my drum were cured, like an old Iron skillet.
When I cleaned it up the next day, the insides were a very shiny Black.
PS: The scrambled eggs, and diced potatoes were great with thick slices of 'Fattie'.