What type of cooking oil do you use in your cooking - 你选对了食油吗?

I have been reading some articles about cooking oil.  However, all of them have different suggestion. I find attached links are rather informative eventhough there is slight contradiction between two of them.
 
http://bbq.about.com/od/grillinghelp/a/aa061607a.htm
http://www.culinary-yours.com/frying_oil.html

I am using extra light olive oil. Sometimes I alternate it with canola oil.  The reason for the alternative is, I simply do not have confidence to stick to only one type of oil.

How do we find out whether canola oil is refined or not?  And, when you read the label, it even contains trans fat.  This means it is not pure, and this means the smoking point is lower than the refined one?  Then, why do some doctors still recommend diabetics to use canola oil?  Do they mean refined / pure canola oil?  How to get the pure canola oil then?  A friend of mine whom has been using olive oil for her home cooking changed totally to canola oil after listening to the doctor's advice when she found out that her husband is a diabetic.

Do you have any information/ advice to share in this matter?  You are most welcome to post your idea here....  Perhaps, we can come to a conclusion?!

The truth is should be out there :-)