Never put atf in the crankcase unless you are about to teardown the engine for a rebuild. That is what that trick used to be used for then some idiot started spreading it as a trick for normal cleaning , BIG NO-NO!
If you want to thoroughly clean the innards of an engine safely go to www.auto-rx.com run 2 full treatments of the stuff, folow the directions to the letter, It does exactly as it says is does, no snake oil.Fast flushes can and sill knock large chunks off and clog passeges, I've had to tear an intake off a small block chevy to replace a lifter that got a carbon chunk in it because of that. Auto Rx cleans very slowly by liquifying the grime to where the filter can safely handle it so that sort of thing doesn't happen. It cleans ring grooves and rings so well I have seen compression on a diesel go from 135 psi to over 400. The stuff does wonders for leaky seals as well.
Sea foam is a fast flush, I would not consider it .
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '92 Ford F350 diesel dually