A few years back, I took my bike to Soth Africa. Whilst there I needed some chain lube, and all that was available in the household was cooking oil. MISTAKE. I then left it the garden for a couple of days, and with the heat of the sun, and the muck on the chain, it was baked almost solid.
My latest chain was gently boiled in some EP90 gear oil, then left to drip, and wiped off. After 500k its still well lubed , as it comes out of the rollers, and a wipe off after a ride keeps it clean. Some black on the cassette but not a lot, just colouring really