GS4 lubrication

[GS4guy]

Just got new GS-4 with DCC on Board (replacing old pancake motor unit that spun its axles and locked its rods years ago).  Bachmann warranty statement in box indicates non-coverage for failure to lubricate.  Included were detailed exploded parts views, but not a word of instruction as to what or how to lubricate.  Any information would be appreciated. Thanks.