Trading markets not charts......
watch the book on which ever two correlated markets you are going to spread, so for cl, notice the forward month, is it upticking the same as back month? less than? greater than? Pay special attention to the pit open.
Once your in a spread, the only reason to...
First, if your only trading calendar spreads I hope you are just trading the calendar products, and not legging in manually.
Second, You should seriously consider why you are trying to apply one piece of analysis to two separate markets..... Your not trading charts, your trading markets...