I’ve recently purchased a Harley sportster XR1200 (oil cooler+ oil cooled heads) and I changed the oil for the first time and used mobil1 20w-50 oil. Within a couple miles the valvetrain started getting louder, soon that sound turned into “marles rattling around in the heads “ sound. I understand that there is more valvetrain noise in the evo engine but this was unacceptable. After checking out the net, I found that this excessive noise is a common complaint of using M1 in a pushrod evulution engine. Being a sucker for sales pitches from net, I ordered Royal purple Max for Vtwins, because I was told it was good at keeping the HD pushrod valve train chatter at a minimum and it was synthetic. While I waited I put in some regular (cheap) penzoil 20w-50 dino automotive oil- and to my surprise the valve clatter became much softer under an engine load. It was great to ride! I recieved the RP and after about 70 miles the valvetrain has gotten louder (not as loud as M1, but louder than the cheap pennziol 20w50), nevertheless- it getting close to my ‘annoyed threshold”. So I ask, is there an conventional oil that proctects the Evo engine decently, but offers a quiet vavletrain? Option 1 : drain a quart of RP out and add a conventional 50W- kinda like blend? Option 2 : Stick with a non-synthetic oil: which is the quietest?