Duh...didn't finish my 1st coffee. Chain oil is termed a "free-loss lube", meaning it is expected to end up in the enviroment. I work on power saws in lumber camps, and tried motor oil (nothing wrong with it for chain lube), but it seemed like I had to readjust the 066 oiler matching the fuel tank run out. Basically too much time/effort to reset the oilers and higher cost for motor oil. Bar oil is tacky and sticks to the bar. Motor oil sprays finer/mists so now an inhalation safety concern. Currently the camp is trying canola/rapeseed base oil for the bars...seems to be doing ok. Used motor oil won't destory your bar/chain. Just check the oil reservoir (adjust the oiler). Keep the chain sharp and flip your bar when you file the chain. Clean out the bar's oil holes and bar groove (use a hacksaw blade).