Originally Posted by
mistarose
May a CFII who has a Commercial Multi-Engine rating on his/her Commercial Certificate give and log instrument instruction in a Multi-engine airplane in which both the flying pilot and instructor are appropriately rated, even though the CFII is not a MEI?
The instrument rating and the CFII rating specify "Instrument Airplane" only. They do not specify number of engines (or wheels vs. floats for that matter).
Therefore a CFII who is NOT an MEI can give instrument instruction to a private pilot who has a ME rating. The CFII needs a ME rating and 15 hours (or maybe it's 5?) in that exact make and model before doing this.
In order to teach the INITIAL multi-engine rating (for either student, private, or commercial add-on) you need an MEI.