Stuck lifter?....Risilone is your friend!!
My little Jimmy short-wide's 4.3 V6 stuck a lifter bad...sounded like a rod knocking..not just a minor lifter rattle.
...Changed oil in it..added a quart of Risilone oil treatment..and let it run for a few minutes...and it quit the lifter knock.
Risilone has fixed up my 'sticky lifter issues a several times. If it's just a bogus crudded up lifter, Risilone will generally fix it....but it won't fix bent pushrods, flat cams, and cupped-out lifters
The zinc issues wearing down cams and lifters is a real pisser..as I understand it...more an issue with new installed cams than with broken in...long running engines. Solution..run diesel rated oil. As mentioned above..Rotella's good..but lots of diesel oils on the market.
I just found out that Mystic oil(what I've been using)is owned by Citgo now....Hugo Chavez oil...
....Probably be switching brands when my oil stockpile is used up.