I change it every 5,000. Mostly highway miles going to San
Francisco everyday to work. I run out at the lake every Saturday/Sunday for some fun. I use Motul synthetic. Seems
to really last a good while.
Our Acura dealer uses pure synthetic in our '02 TL, and they insist that oil change isn't necessary sooner than 7,500 miles each time. Now, I know bike trannies are a bit more needy, so perhaps 5k - 6k if highway...
On break in (dino) 500, 1200, (synth) 2000, 4000 then from there it depends on how hard it is ridden. The transmission actually lets you know when you should change it. I notice a difference when I shift. As soon as I start to feel it I change the oil. This usualy comes between 3500-4000. If it starts earlier, I change it earlier. It's better to change it earlier, if you think something feels different than not and pay a higher price later.
I have been going every 2500, 8000 miles and a little today.
Dropping it this morning again.( The oil !!)
It is amazing how fast it can get dirty.
But I live in a extremely dusty place.
Lots of tractors running the roads, kicking it up.