The best and most efficient way to clean the chain is when is off the bike.
So first remove it from the bicycle.
-Use gasoline and a brash for a first cleaning.
-Dry the chain with air if possible (use air compressor)
-Put in a pan concentrate dishwash detergent and water and let it boiled
-Put the chain inside the pan and leave her for 2-3 minutes. This will remove any dirty or oil from the
links and from parts that were not possible to removed with the gasoline
-Remove the chain spill the water and clean the pan
-Put water in the pan boil it and put the chain inside. Boiled water will rinse the chain without
produce any rust.
-Remove the chain
-Use a wax heater and put inside oil with Sae 80 or thicker.
-When the oil became thinner put the chain inside and leave her for 2-3 minutes.
-Remove the chain and hang her overnight
Next morning the chain will be ready to put her in the bike.
Repeat the same procedure about every 3 months or 300 miles.
Instead of the oil you can use paraffin wax but oil is superior than the wax.
Please note that I use this procedure for decades and I never had any problem.
But you need to be careful and use any possible protection as what I described involve flammable liquids .So proceed with your own risk.