Hey Dan...remember you asked for this...
I stay completely away from 99.9% of most
petroleum products for just about everything except working engines and then I use synthetics...Used motor oil is a toxic material and not something I would ever recommend as a "permi." (Yes there are organisms that can eat it...not before it causes issues in most cases.)
My chainsaws (both cutting and milling) get the bar oil I have used for over 20 years...Canola oil, and/or Peanut oil (if I can get a deal on Peanut in bulk I really like it.) Yes there is a "little" gumming at times...never any real issue of note on that though, and I run the biggest chainsaw engines with bars over a meter in length full throttle...often several tanks in while milling or logging.
For tools, most often is either
flax, or Tea seed oil (what most layfolk call linseed and Camellia) depending on use and quality of tool. Beeswax has its place here as well...There is also a place for walnut, and coconut oils...Also swine and bear fats works wonders as does Seal oils...
Natural lipids are a wonder in many ways...from addition to lime mortars and plasters of all types to making finishes...can't really live without these lipids...