using synthetic in no way voids a warranty ( I believe this might be covered under the Magnuson-Moss act from the 70's ) because it meets and exceeds what the manufacturer recommends and other oils but you are right,to each his own.Cactus Aviation recommends synthetic from the start,they must have Germany backing them or they couldn't make that statement.Aircraft International recommends petroleum based for break in,they must have Germany backing them or they couldn't make that statement. See what I mean, There is no absolute wrong or right but just a new alternative to the old school ways!! I have never said synthetic is the only way just that there is a differen't way besides what we have all done in the past.
plus I'm just defending myself from former remarks saying I am mis informed and don't know what I'm talking about. I believe I have done enough homework to prove otherwise/but then again maybe not.