That bypasses the question about idea that synthetic will actually stop lifter rotation.... I would like to understand this issue, rather than just blindly accept it.
BTW, none of the above cam makers explicitly list the use of synthetic oil as a reason to deny a warranty claim in their warranty statements. Nor do they say anything like that in their FAQ or apps info. Crower does recommend against synthetic in their FAQ's but then says if your car's owner's manual says to use synthetic, then 'you may do so'.... that's darned inconsistent! LOL
BTW, this seems to be a reasonably objective article on these issues, free from odd claims or hyperbole....