Fully synthetic or part synthetic?

[PieEater]

Oh sheet you called it, I'm real stupid and just can't think for myself so I just have to listen to Mr Yamaha's advice and can't pay no mind to smart folks like you tellin' me it's fine to use mineral oil as long as I be changin' it every year, or I can skip every 3 changes if I use that semi synthetic oil. You know what they say about us dumb people, you just can't get them to change their ways, and I must be real dumb because I aint never going to take your advice. I hope there are more dumb people out there like me who listen to that nice Mr Yamaha when he tells them how to look after their motorcycles rather than clever folks who say you'd be better off doin' your own thing. And that's 'bout all I have to say 'bout that.