i would do an engine flush when swtiching to fully synthetic. Example. put in fully systhetic with new filter, rev engine for 5 mins, drain out and put new oil and filter.

 

for what it is worth the sythetic.
has a problem when the bike is stored from all i can find out. if the bike sets for weeks and not fired up the syntetic is so slick it tends to fall off of the cramk bearings leaving you with a dry bearing when you crank up. their is nothing wrong with using sythetic in the summer when you ride all the time but i would not seat it up for cold weather storage with it. just some research i done on the oils