The chain must be oiled at regular intervals of every 50 hours of use to prevent stiff links. You can lubricate the chain with a teaspoon of purified mineral oil applied to a paper towel. Rub the entire length of the chain and wipe off the excess oil, so it does not stain your flooring.
Beware that oil soaked clothes can burst in flames – take your precautions. Never clean the chain with any kind of cleaner or solvent like WD-40.