You really should change your oil after each weekend trip. Like the dunes or cinders. If you are just riding in the backwoods, then about everyother trip. Maybe streeeeeatch it to three. But no more than that! Then change your filter on every other oil change. Filters are cheap! 5 of em on eBay for about $12. And never run synthetic! Belray is good stuff. And you can always play it safe with Yama stuff! That motor is very close tolerance. there isn't much room for trash in your oil. It is a 4-stroke, but it is a "race bike". They require lots of care and maintenance. If you don't, it will treat you like a 2-stroke...

 

Every 10-12 im guessing

 

Every 100 hours my V gets a new gallon of Rotella dino oil.

 

Every 20 hours for me.