Most things I will try at least once. About 3 months ago I decided to stop planning and talking and put a plan into action. I came across some used cooking oil, I dumped it (filtered) into my heating oil tank. Things seemed fine, the water also seemed hotter. Maybe it was the satisfaction of taking a first step into non reliance on Heating Oil. Anyways, my heater started misfiring; it eventually shut down. No big deal, I pulled the filter off; cleaned it. No good. So, I went the next step and tried to remove the nozzle. I had a heck of a time, when I managed to wrestle it out; it had a caked on varnish. Well, I cleaned it all up and reassembled. But I also decided, never again...
Jon