My ol wasserboxer has its share of lifter noise.  Especially as I
reach the end of the 3000 mile oil change interval using castrol
20w50 and mahle filters.  I was wondering, as I approach the next oil
change in a few hundred miles, if I might add something to the oil to
help clean the engine internals a bit without causing trouble.  I've
heard SeaFoam and Marvel Mystery Oil mentioned on this list in the
past.  any recommendations?  I'm thinking a one time treatment here.

Thanks,
Edward