Ditto. There is a can of MMO next to my tool box and my air tools get a few drops before each day of use.

There was a time when the additive package in motor oil was somewhere between very poor and non existent. In those days the situation was aggravated by colder thermostats and draft tubes allowing for more moisture buildup in engine crankcases. In those days MMO was a drastic step that had to be taken under certain conditions and was about the best we could do. There are some folks who don't realize just how drastically all of this has changed, thus they cling to the old ways.

NOW, however, engines have very good crankcase ventilation and higher temps which boil away more moisture resulting in a lot less acid buildup. Add to that the EXCELLENT motor oil additive packages in premium oils and you have a combination that will never need such drastic cleaning if the oil is kept changed.

For those drastic cases where oil has not been changed to a point of buildup, a good oil, preferably one of those I have noted, changing very often and always draining hot for an extended period of time is the best and safest step toward cleaning the engine IMHO.

The Gunk is a decent way to clean a gunked engine, but I would personally use that approach sparingly and VERY carefully as you point out.

Have a great day,