My 1974 Euro Pantera has had a noisy valve train since I got it two or three years ago. It has a hydraulic roller cam, roller rockers, and guide plates for the push rods. Soon after getting the car I put in a new set of Comp Cam lifters when I found debris (oil filer element?) in two of lifter oil inlets. Since then I have adjusted the lifter preload numerous times in an effort to quiet down the valve train without complete success. I finally tried Liqui Moly for hydraulic lifters and it worked. Because I have a high capacity oil pan it took two bottles of Liqui Moly. The noisy lifter sounds were immediately reduced and nearly eliminated. If you have a lot of lifter noise it may be worth a try.