Can I use common vegetable oil (e.g. rapeseed/canola) for chain-and-bar lubrication in a chainsaw?
Yep. Yesirree.
Not being a fan of dumping petroleum into the woods (mine or otherwise), and considering that my saw is electric* (and therefore operates at slightly slower speeds), I've shifted to using common cooking vegetable oil instead of used motor oil, as I had been. Over a number of outings it has performed well, with no heat buildup, noise, excess fling or other anomalies.
This is a far different scenario than what happens inside an engine, for example, so it's probably not as critical as oil choice is there. One article shows the viscosity of vegetable oil to be comparable to that of conventional multi-grade motor oil, and slightly higher than PAO (synthetic) motor oil. Another study concludes that vegetable oil is a perfectly viable alternative.
Technically speaking, olive oil isn't vegetable oil in the sense that those mentioned in the question are. It's far more aromatic and prone to unpleasant side effects if used in tools. I don't recommend its use in chain saws.
That said, I don't have any empirical evidence to tell you whether it is having a detrimental effect on hardware life in my case. It's entirely possible that I'm subjecting my bar and chain to increased wear, but I haven't noticed any (chain adjustments are more or less typical). Regardless, I consider it worth the environmental and financial benefit.
YMMV.
* Ryobi 40V 14&quot;