If chainwear is gong to be important, take a chainguage. They are just small, thin bits of metal.
Diesel is good for cleaning chains and you can salvage enough from what is left in the hose of a gas-station pump. Diesel in not good for your skin.
If you have to use car engine oil (from the remains of new cartons in the gas station waste bin), dissolve it in a little diesel for better penetration.