The waste oil heater can burn waste oil (used crankcase oil up to 50 wt), 1 and 2 fuel oil, hydraulic fluid, automatic transmission fluid, and synthetic oil (up to 25% blend). BTU is calculated by finding the cubic footage (LxWxH) then multiplying that by 3.5. Attached as a link under the product is more information about the MX-150, MX-200, and MXD-200 model. The MXD-200 model is ductable meaning you can plug it into any duct. **Be careful to stay away from gear lubes because burning them will causes more maintenance. Hazardous waste is illegal to burn. EPA USA does not allow burning of brake fluids. There is no UL safety standard for burning used cooking oil (vegetable oil).