What solvent for cleaning immersion oil off of microscope objective lenses?

Over the years I've asked a number of people servicing microscopes this
question, and have gotten somewhat differing answers. Some recommend the
commercial green stuff that comes in little plastic bottles, while others
prescribe anhydrous methanol or ethanol.

All have agreed that xylene should not be used because it dissolves lens
mountings. Ethyl ether is much too flammable to be kept around a microscope,
or anywhere else in a histology laboratory, and acetone is a serious fire
hazard also.

Most important is to clean lenses frequently - after every use if the oil
lens is used only occasionally, daily if in frequent use, and probably on
every shift for heavily used microscopes in hematology laboratories.

A real problem is the fond belief by many pathologists that real men don't
clean microscopes, and among technologists that they're much too STRESSED to
bother with such details.

Bob Richmond
Samurai Pathologist
Knoxville TN