in my experiance if it is a crossflow motor 9 times out of ten the cam is worn not the lifters. when replacing the head on my xf ghia i did the lifters aswell due to a lifter noise, the new lifters were quite for a while but the noise was back within a couple of months. that was five years ago and the noise is no longer there since i changed the oil i use. i now use castrol fmx 15w40 i think. is a semi synthetic oil and is thinner than the helix i was using. but has quietend my engine. nulon lifter free works well but for the best results change your oil and filter before you use it. use it wit fresh oil as you waste the cleanig agents in it on the dirty oil instead of the carbon deposits. i use at least 1 bottle a week at work this way with a 90% success rate.