I started using used motor oil 30 years ago when it the oil was 10w40, the last 15 years my car said to use 5w30 which is a little thin for my tastes so from then on I split it 50/50 with bar oil, but when I buy a new chainsaw I use only bar oil till warranty is over. I drain my motor in a clean container, dump it in another clean-ish container, let it set for a few weeks so if there's any dirt in it, it will settle to the bottom. I dump out the last pint or so, then mix the rest with new bar oil. All together I go through about 10 gal. of oil on the chainsaw bar a year, with bar oil $10.00+/gal., in a few years that adds up. Out in the country there's only a few good ways to use used motor oil, for me chainsaw bar is one.
I've had 8 or so chainsaws, and so far I had 2 sprockets break on the bar, mostly engine problems, also I had one tree falling on saw problem, but never had oil pump problem, yet. Now I have 10 gal of 300 hr. old tractor trans. oil to use for bar oil, its been through the tractor filter, drained in clean containers, should work pretty good. I cant wait to read all the complaints from the bar oil police.
I've had 8 or so chainsaws, and so far I had 2 sprockets break on the bar, mostly engine problems, also I had one tree falling on saw problem, but never had oil pump problem, yet. Now I have 10 gal of 300 hr. old tractor trans. oil to use for bar oil, its been through the tractor filter, drained in clean containers, should work pretty good. I cant wait to read all the complaints from the bar oil police.