How do you lubricate 1518 1Y rear bearing?

thanks for the reply Jerry, I will search RC monster for other posts on this topic. However, the front bearing definitely isn't sealed and is just a standard metal shielded bearing that will need to be constantly lubricated to prolong its life. I'm concerned about the rear bearing as i know it will eventually run dry and wear out.

I have a TREX 450 electric helicopter as well and I lubricate both motor bearings (metal shielded) every 5 flights or so. Similar RPM, similar metal shielded bearings.