I continue to read all over this forum that some are choosing a heavier weight oil, because it "smooths out the engine" and "sounds better". I also read a lot that many believe a very good 20wt Synthetic is just as good or better than the heavier weight oils. I feel certain that a top notch 0w20 will keep an engine running far beyond 100k miles, if not 200k miles. But, will a 5w40 better protect an engine to go beyond 200k miles? We all know that a 5w40 will sound and run smoother than a 5w20. I am just wondering, is there a correlation between a 'rougher sound and feel" to increased engine wear?