On the last three bikes I have bought new (2006,2010,2011 YZ450's) I have tried too maintain the steering head bearings. On the 06 I had to replace both due to not greasing them after each year. When I bought new ones for it I kept them greased but the top bearing would still have like burnt spots on some of the rollers and on the race. When I bought the 2010 model I greased both bearings before I rode it and the top bearing still went bad in a years time. Had the same burnt look on the race and the rollers (like surface rust). When you took the front tire off and the forks off and turned the handle bars you could feel that roughness (notchiness). When I bought my 2011 model I did the same thing. Took the steering stem out and greased the bearings before riding it. Now at 17.4 hours on it I thought I would check them and sure enough the top one had the same surface rust on the race and the rollers and had that notchiness feel to them. I just took 800 grit sandpaper and cleaned them up a bit which helped and repacked and put it back in,but could still feel some notching but not as bad. What grease would be good to use for the top bearing? The bottom ones were fine. I'm useing the Moly disulfied soap base that the manual calls for. I have tried the Red extreme pressure grease before and had good results with it but changed to the Molly. The BellRay water proof marine saltwater grease didnt work either.