Dual fuel generator - does it need gasoline or can it just be run on propane?

[deserteagle71]

propane delivers more energy (BTU's per volume than gasoline does)

False! Here's the correct answer:

What propane does have is a much higher octane than gasoline - over 100. I was able to advance the timing on my old GMC van when running propane to make up for the lower energy per gallon.