Method of oil recovery

A method of recovering petroleum from a subterranean petroleum-containing formation, comprising:

• providing an injection well containing a flow path in fluid communication with at least a portion of the petroleum-containing formation, providing combustion byproducts from an internal combustion engine, rendering the combustion byproducts relatively inert by contacting same with manganese and/or manganese dioxide, pressurizing the combustion byproducts to about 1,500 p.s.i., heating the combustion byproducts to a predetermined temperature of at least 400.degree. F., adding fuel gas to the combustion byproducts at the same time that they are heated to a predetermined temperature, and injecting the combined combustion byproducts and fuel gas into the petroleum-containing formation to increase the volume of the petroleum, to heat the petroleum to reduce the viscosity thereof to enhance the flow of the petroleum and to pressurize the petroleum to help force it to the production well so as to increase the recovery of petroleum from the petroleum-containing formation.