I am interested in trading crude oil, heating oil, and gasoline - probably some version of a crack spread. Trying to do a little research at this point. I have to show my ignorance here. Which contracts are actively traded? It seems that CL (WTI) is the most active. I get a llittle confused by the other crude contracts and the various heating/fuel oil and gasoline contracts on the various exchanges. If someone could give me some advice, I would appreciate it.