I will never, ever go back
I've been using vegetable oil for 4 years now, both Summer and Winter, in both the 346's and the 395's and power pruner.
Just today I did one of those really stupid things, where you do gas and oil, pick up your saw, but forget to put the oil cap back on. Didn't notice until I'd drenched my right-side chainsaw pants and boot, and the rest on the ground. I seem to do this at least once a year. Anyway, no big deal because it was only vegetable oil.
I don't recommend veggie oil for guys who don't run the saws regularly (it will oxidize, given enough time). For those of us who run them daily, or even a few times a week, I highly recommend it, as it is run through long before there is a chance for it to oxidize. I also suggest it for both health reasons, and environmental reasons.
If you don't give a crap about your health, or refuse to ignore that you're spinning off atomized particles of oil into the air, which you inevitably breath in, then put in used motor oil, like Timberjackboy. It's cheap, it stinks, what the heck? You're also probably aware that the 'bar oil' particles end up on your gloves, hands, hair and clothing. Wash your oily pants with socks, shirts and underwear and minor amounts will cling to those non-oily clothes, as there is no perfect detergent, and petoleum-based oil is not very soluble. I would guess that some might even stick to the inside of the washing machine. Just a guess. It doesn't matter, though. Your wife doesn't know when she goes to wash your sheets, or your children's clothing. As long as nobody knows, it's OK....
I apologise if the truth seems somewhat sarcastic. It's not a matter of whether you believe that stuff or not. It simply is what it is.
Having used nothing but vegetable oil as my bar lubricant for so many years now, I will gladly and freely offer to answer any question that anybody has. I may not know you, but I care about you. I also care deeply about the environment, but I don't particularly care about stimulating the economy of the petrochemical industry.
Bar oil leaks, bar oil gets spilled, bar oil ends up on the ground, in the sawdust, on the firewood and on the ground. That's just the truth, and you all know it.
If you REALLY care about the oil oxidizing, break a Vitamin E gel cap into the next gallon of corn, soybean, canola, peanut or vegetable oil you buy. Vitamin E is a powerful, fat-soluble antioxidant. I personally have never done this because most food oil manufacturers already add it to extend the shelf life. Veggie oil costs around $5 a gallon. I'm ready for any questions.