As suggested earlier, you should just allocate a VERY small amount of money and actually do some trades. It won't take more than a month or two to realize how quickly and easily calendars can lose money. We could tell you how and why it's not fool proof, but that's not the best way to learn. The best way to learn option trading is to get in there, again with VERY small allocations and learn from trial and error. Very often the people who are willing and eager to "teach" you, are the very same people who don't know how to structure profitable trades and manage them. In your case, error will very likely come quickly, and you will begin to develop an understanding and turn it into personal trading rules and systematic strategies that do work in the future. Good luck sir !
I suspect the OP cut his teeth on calendars with stocks. An awareness of the forward curve is the necessary ingredient. Additionally, skew behavior is not as predictable though it seems to persist for longer durations.
The 1M switch is contango as donnap states. It's +100 to 105 which is huge for CL in the 40s. You would want to use same strike if bullish CL. It looks good to you because of the contango, and no, the thing is not DN when trading ATM. Neutral delta would be a 42/43 diagonal call. You're long vol, long the switch (futures calendar), and short gamma. Basically you want vol to increase; the contango to widen; and price to settle near the March strike. It requires stat and implied vol to diverge. There is nothing special here -- it only looks good because the switch causes the March strike to be ITM.