As Galen says, I've run everything from Flora virgin Palm Oil (Got a drum given free) to 2 stroke oil, to used gear oil to used axle oil and any other old oil I can get ... all the old oils I run through a couple of home-made filters. Colander on top of a large open drum and a pair of the missus' old tights, gets all the large and claggy bits, then through a fuel filter before putting it in the tank. I also always mix it with diesel .. and always add it when there's (about) half a tank of diesel already in ..
Paul, you should add a 'rare earth magnet' to your home made filter stack, you can find extremely powerfull ones in old hard drives.
Bloke I knew filled his Jag chassis with the stuff. About 8 years later someone ran into the back of him, and the body repair people had quite a damp, oily surprise! No rust though...does the motor smoke more when you driving going to try it saves taking it to recycling can you use it to preserve the under side of the old girl as well or is that a no no
Ive heard of people mixing old engine oil with diesel I want to know if you can mix old auto box oil (dex111) as Ive just changed the fluid on mine and have about 10 ltrs of old stuff and will have some engine oil soon as I get round to servicing it