In our avaiation class we used Marvel Mystery oil for cleaning out cylinders
after honing.  It was great for getting the really small particles out of the
cross hatching.

We also debated the difference between it and ATF.  I have used ATF in diesel
VWs for injector cleaning (Type F) and 1/2 quart of dexron mercon in motors
to quiet lifters (like MMO does).  Seems to work as good and I always have a
bottle of ATF handy while buying MMO is a special purchase (although it is
worth having around).
Have fun and somethings are better left as a Mystery :)
Ken Wilford
Van-Again
John 3:16