I have also heard of using Dawn dish detergent - but only when cutting HDPE pipe (for waterlines and such). I have also heard that it absolutely destroys chains and oilers, and they only use it because of environmental concerns, and because oil on the pipe would potentially compromise the integrity of the heat fused joints.
Why am I sharing this? Because people can pour all kinds of crap into the oil reservoir, and it might work, at least for a while. That doesn't make it right. I happen to use commercial B&C oil, but in cold weather (below 20F), I definitely have issues with the oil being too thick. I have found an oil that works well in cold weather at my local hardware store, but I just can't remember what the brand is off the top of my head.
I can definitely see using canola, especially in warmer weather, around the house. But in general, I don't see anything wrong with commercial bar & chain oil.