The large building waste oil heater can burn waste oil (used crankcase oil up to 50 wt), hydraulic fluid, automatic transmission fluid, 1 and 2 fuel oil, and synthetic oil (up to 25% blend). To find desired BTU calculate cubic footage (LxWxH) then multiplying that by 3.5. The MXD-300 model is ductable so you can plug into any duct. **It is illegal to burn hazardous waste. Stay away from gear lubes because burning them will causes more maintenance. EPA USA does not allow burning of brake fluids. There is no UL safety standard for burning used cooking oil (vegetable oil).