26th Aug 2018, 09:12

Spray Armor All all over it and then soak some rags and lay it on top for a few days so it really soaks in.

26th Aug 2018, 13:40

You could try spraying WD-40 (not ArmorAll, LOL) on it occasionally, but there really isn't any "preventative maintenance" for a harmonic balancer beyond ensuring that the crankshaft seal is not leaking. Oil getting past a bad seal can get on the rubber part of the balancer, causing it to soften and shortening its life.