Dan, thanks again. The chain, rails, and tensioner were changed on my car 2 years ago by a mechanic so he's the one with the chain crimping tool ;-) If I hear any inkling of the slap again (haven't heard it since I changed the oil to Mobile One, lighter weight 10W-30 from conventional 20W-50 but that may be coincidence or weather/temperature related don't know) I'm going to just change the tensioner.