Chainsaw Bar Oil Question

If you think that bar oil was expensive the canola oil is about the same. Go to Wal Mart, or any home improvement store for bar oil.
BTW, chains don't stretch, the rollers wear and that is what causes what we like to call, "stretch".
The Red Line "Shock Proof" gear oils are very clingy like bar oil. They remain so after use, also. I use it in my M/C transmissions and bevel drives. We used it in a friend's dirt stock cars. It was hard to remove diff gears because they were hard to grab. But, it is very pricey. If you cut a lot it may pay for itself.