Some years ago, in the time of 5 or 6 cog freewheels and 3/32" chains, the group I was road riding with ~ 3hrs/day got good chain and freewheel life by purchasing 3 chains each time we replaced a cluster. We cleaned the cluster and mounted a thoroughly cleaned chain at ~ 200mi. intervals (more frequently if ridden in rain, or on dusty roads), rotating among the three chains. The cluster and chains wore at about the same rate, clusters lasted longer than had we simply worn out one chain at a time, and we always had one or two clean chains at the ready. We cleaned either by shaking in a can of kerosene or in an ultrasonic bath, replacing the solvent a few times, and typically relubed with 20wt. oil, wiping off most of the excess. Memory says clusters lasted ~ 5000mi, but could get more by replacing the fastest wearing sprockets (or groups), usually the smallest ones, as they became noticeably worn. Today there are all kinds of pricey lubricants available, but I suspect any lube that remains inside the chain should be okay provided it's not allowed to get too dirty.