BTU's for various fuels/oils
No. 6 Fuel Oil (used motor oil) = 150,000 BTUs/gallon
No. 2 Diesel Fuel = 140,000 BTUs/gallon
Kerosene = 135,000 BTUs/gallon
Jet Fuel = 130,000 BTUs/gallon
Biodiesel (B20)= 128,000 BTUs/gallon
Gasoline (mid grade) = 125,000 BTUs/gallon
Aviation Fuel (Avgas) = 125,000 BTUs/gallon
Ethanol = 85,000 BTUs/gallon
Methanol = 63,000 BTUs/gallon
This information was obtained from a 15 minute web search. I couldn't locate anything specific to 2-stroke oil - yet. It would appear that the heavier the oil, the more BTU capacity. Here's an interesting read:
http://www.sea-doo.net/techarticles/oil/oil.htm