You know, that's not a bad idea. I was thinking about using a heat gun to get the heavy stuff off then possibly a citrus based cleaner to get the rest.
I did a little google searching and discovered acetone and turpentine are used for removing linseed oil from wood, brushes, etc. I going to experiment with that, hot water and heat gun. You mentioned diesel fuel, I'm wondering if kerosene would be worth trying.
I think the key is that you want to saponify/emulsify the oil/varnish. Ordinarily I would use a strong base like NaOH but lye will attack aluminum. I think something already saponified/emulsified like Murphy's Oil Soap and/or waterless hand cleaner / Gojo / even grease like what comes in a tube would probably eventually break the sh!t loose. Some kind of fish oil might be another option...when you cut up a fresh tuna, they are as oily as greased pigs, but for some reason, all the grease rinses off your hands with just water (no soap needed)....I suspect there's something in the tuna that emulsifies/saponifies the fats...maybe the omega-3 fatty acids? When you cut up an actual pig or deer, you need loads of soap to get the fat off your hands and the knives, etc...this becomes a major PITA because the knives get so coated with fat that they won't cut meat worth a damn...it's like trying to cut up steaks with a candlestick...anyway, the point is, I would look at soaps more than solvents...if I did use a solvent, I would look at something non-polar, like xylene...
That depends on what the plastic is made of.
I would try mineral spirits. It's the solvent used in a lot of tung oil wood treatments, as well as clean up for same. It's safe on plastic and painted surfaces, as well as bare metal.
It don't do a thing to polymerized Stihl bio-bar oil.
If its linseed oil watch out , I use linseed oil on heavy rust it, sinks in and solidifys
