I recently changed to fork oil in my front forks for the first time. I did not heed the warning. My '03 has 7200 off-road miles on it in 3 seasons. What was interesting is, when my bike was new, about 500 miles, I blew a fork seal. It was replaced under warranty, but even though I argued, they only replaced the one seal that was bad. Anyways, I drained the forks by opening the caps, pumping the forks a few times over an oil pan, and then I hung them upside-down for 24 hours. The side that had been replaced was still decent oil. It was really dirty, but it was still oil consistency. The side that was still stock, on the other hand, was in bad shape. The oil had started turning to "snot". It was gross. Anyways, after 24 hours of hanging I got 20.5 oz. of oil out of each fork. The total stock capacity is 21.5 oz., plus I had previously added 10ml to each fork. So, I got almost all the old nasty oil out, and since that stuff was NASTY, I'm going to start changing oil every year.