Often in vegan cookbooks I see that recipes ask for, say, canola oil, or coconut oil, or whatever it may be. I've never seen either of these oils in supermarkets or health food stores here, and was wondering if they can be substituted with other oils without problems in recipes? What are the main criteria for choosing one oil over another? I'm aware that certain oils should not be heated - flax for sure, and olive oil shouldn't be used to deep fry - but other than that I'm pretty ignorant about the properties of the various oils. If anyone can provide any info I'd be really grateful.