Science Buddies: "Ask an Expert"

Can someone help this idiot(me)?
What do you get when you use Methane gas as fuel for a combustion engine?
Will it be only Carbon Dioxide? (I assume because of the oil acting as lubrication for the engine there will be other fumes as well, right?)
I know CO2 is beneficial to plants but I am also curious about the oil/lube in the engine whether harmful or not.)
Thanks in advance.

Any combustion reaction with hydrocarbons will produce carbon dioxide and water. The chemical reaction for the combustion of methane is: CH4 + 2(O2) --> CO2 + 2(H2O). The methane combustion reaction alone is relatively harmless. However, in an engine, the combustion of methane could react with the surrounding air, which then produces many harmful emissions. The heat from the reaction also causes some fuel to evaporate instead of combusting, which also adds to the harmful emissions.

You could experiment with the reaction and different temperatures or pressures and see which combination is the most eco-friendly.