Well it matters a little.... Because some of the cheaper ones like Fram dont have the anti-drainback valve. But that mainly affects your oil pressure at startup, which directly affects the valve train noise at start up. My assumption has been that the clatter comes directly from the use of syntheic oil. Almost everyone that has clatter uses some form of it. Where as the ones with no clatter, usualy use dyno oil. I dont have any clatter and use dyno oil. Its not a total proven point tho. Naji did a little survey a while back on this. And if i remember correctly the trend showed that it was related to the syntetic oil. It doesnt hurt it but is anoying, kinda like starter squeel.