Ron, I have used Canola on the bar with some mixed success-
First the bad news: The nose of the bar just behind the sprocket where the chain first comes in contact with it shows some accelerated wear, I blame this on the low viscosity and the lack of a tack additive.
The good news: The chain seems to love it, I have not had to adjust the tension for many hours after the initial stretch on a new one. It seems to have low friction in the groove, heavy cuts at the limits of the saws power get the bar only a little above skin temperature. It will not hurt your trees or your grass, this is the reason I originally tried it because the regular stuff was leaving dead spots on my lawn.
If you decide to use it, let me know your results, I suspect the bar I used may have been on the soft side and would like to know other peoples experiences with using a veg oil on their bar.