If it's running well, don't lubricate it. One of the worst things you can do to a locomotive is over-lubricate it. If it's new, it's probably not in need of lubrication.
Your locomotive "coasts" to zero likely because it has a flywheel. That's a good thing, because it helps the locomotive run smoothly by allowing it to coast over dirty spots on the track and start and stop with minimal jerky-jerky movement.
Hope this helps,
DFF