NO, NO, NO, NO!! DO NOT use oil in place of water in the pan! This is an invitation to disaster. If that oil spills over on those hot coals, you WILL have a fire, a big fire that will be very hard to extinguish.
One of my many BBQ blunders occurred when I tried refilling my water pan in the dark. I had three shelves of rib tips (scraps from making StL cut spares) that had marinated in a solution with a high oil content cooking on the WSM. The rendered fat from the ribs and the oil from the marinate that had accumulated in the water pan was "lighter" than the water. When I overfilled the water pan, the oil and fat hit the hot coals and ignited. The flames from the oil and fat heated the water pan to where the water boiled over spilling even more oil and fat on the coals. I had flames two feet high coming out of the WSM!!! It took several minutes for the fire to go out. Luckily there was snow on the ground where I was cooking when this happened so I did not burn anything down.
It is too big of risk to try and put any type of cooking oil in the water pan. The heated oil may not get past its flashpoint in the pan, but if it spills on to the coals it will catch fire. The fire can then get hot enough to ignite the oil in the pan and then you are going to have a dangerous fire.
Beers to you,
Juggy
