Dan, your comment that the recycled oil may be a little short on BTU's for hard use makes sense. The thought has occurred to me a few times "wondering how SVRy 19 pulled near tonnage loads up on the WP&Y when oil fired?" in that the two times I had the chance to fire it with near tonnage going to Sumpter to keep up steam the fire really filled the firebox and tended to have short flames licking out around the fire door plus even with the dampers wide open there was still some drumming. It occurs to me after your comment, that with a hotter fuel like #6, the firing rate in terms of GPM of oil going into the firebox would have been a bit less and therefore smaller flame size and less of the problems I experienced. Does that sound probable?