Can you substitute butter for oil when baking?
Yes. you can also use margarine, shortening, etc.
It depends on what the oil was for. If it is a recipe, especially for baking, you can use butter as substitute for oil. It is not recommended to substitute butter to fry something because it tends to burn in a hot pan, you should use oil to fry. Yes is can! Just don't use as much oil as butter. Butter is thicker than oil so don't make it too sloppy.
You can safely substitute liquid oil for solid shortening in baking ONLY if the recipe calls for the shortening to be melted first. You can substitute butter or margarine for shortening ( 1 cup + 2 Tbsp for each cup of shortening). You can also substitute 1/2 cup applesauce or prune puree for each cup of shortening.
That depends on what you're making. If you're baking, I wouldn't risk a substitution. Baking is very precise, there is a delicate balance of ingredients in order to achieve the desired chemical processes and the right result. If you need a substitute for butter in a COOKING recipe, say for a sauce, or to pan fry vegetables, that's different. You could probably substitute margarine, Smart Balance, or a light and tasteless oil.
Canola is not a dairy product so there is no butter in canola oil. However if you are looking for a substitute, you could use a tablespoon of butter instead of a tablespoon of canola oil. If you were using cups rather than tablespoons, you may need to make a slight adjustment on the liquids. http://canolaeatwell.com/ask-judy-canola-oil-and-baking/