IMO it depends on the type of burner your furnace has. If it's the
modern "spray nozzle" type, I wouldn't risk getting foreign matter into
the fuel for fear of clogging the nozzle (think auto fuel injection
here). If it's the old fashioned "pot burner" type, it's probably OK,
but you might want to inspect the pot every few seasons, for crud
> Also, does anyone know if it's OK to put small amounts of waste oil in
> standard "oil fired furnace" (home heating oil/ diesel fuel)?