Originally Posted by kawie_guy
Not much. One of the gurus claims that he sees spun rod bearings several times a month, and 90% of the time, the owner of the machine said they were running synthetic.
He invites people to swing by his shop if you're ever on the interstate running through Pennsylvania, and he will show you his collection of spun bearings. This is a guy who's world famous for building some of the fastest Kawasaki and Can Am engines on the planet, and he's got a very loyal following.
I may not be a an engine building guru, but I know the chemistry and physics of oil, and what these guys say makes no sense.
That proves nothing unless you know what percentage of total customers use synthetic oil.
I'd guess a large portion of Harley owners use synthetic. It's not like most of those bikes are bought/used as cheap transportation, they're toys that their owners paid a lot for and take pride in. They probably aren't going to cheap out on oil for them.