I used compcams break in lube on all push-rod ends, lifters, rocker tips, etc. Everyone i talk to says putting new lifters on a used and undamaged cam is no problem. Both VP and a rep at Isky said it should be no problem either. A new cam with used lifters is a very bad idea though, not that i would ever attempt that. Again i only have 1,500 miles on the cam using proper break in lube and the lifter bottoms show no unusual wear patterns. The wear was the push-rod into the top of the lifter, possibly because of a hardening defect or mismatched radius between the lifter socket and push-rod tip.