Pour cooking oil onto paper towels. Using the towels, wipe the interior lid of the smoker and the cooking grates until the parts glisten. Do not use oil on any part of the grill except the inside cover and the cooking surfaces..
Load 10 pounds of charcoal into the smoker firebox and start a fire with lighter fluid.
When the coals burn white, close the smoker cover.
Adjust the top and bottom vents so the air flow keeps the smoker interior at approximately 250F, then allow the smoker to cook, closed, for two hours or until the coals burn out.
Allow the cooking grates to cool completely, then coat the top and bottom of the surfaces with cooking oil once more.
Load the remaining 10 pounds of charcoal in the firebox and start a second fire.
Close the grill and open the top and bottom vents as far as possible to reach the maximum internal heat, which is typically 450 to 500F.
Close the smoker with the cooking grates in place and let them bake for one hour.
Open the smoker lid and allow the unit to cool. Your smoker is now cured and ready for use.