Got the '06 Feejer about six months ago and all fluids were recently changed before I bought it. The bike has 44k mi. on it. I've been riding it as much as possible for fun. Ride to work only once a week, too much freeway/traffic etc. Anyhow, have noted the shifting wasn't as silky smooth as it ought to be (despite adjusting the lever) and the engine seemed a bit noisy. I decided to change the oil to see if it would improve things a bit, and I am happy to report it did. It had synthetic oil in it, but I took it back to dead dinosaurs, 10w40 Valvoline, moto specific. The shifting is smooth and light, the rattley sound is gone, it seems to rev quicker, just all around seems to run better.