Originally Posted by Pleiades

Filter - Always used genuine part bought from the local dealer, last one cost me �7.49. They're only a pound or so dearer than the cheaper aftermarket ones, and the same price (or a little cheaper) than a K&N.

Oil - I've stuck to 10w40 Motul 5100, which is the same stuff as the Yamalube that the dealers use. Cheapest place I've found it seems to consistently be Busters ebay shop these days - �24.95 (including free delivery) for 5L.

Drain Plug Washer - I'm still using the same ones the bike came with! It's five and half years old and has seen probably ten or more oil changes. I've just re-annealed them each time by heating to a dull-cherry red colour and then cooling naturally. I would buy one, as they're only a few pence, but whenever I change the oil I seem to have forgotten to get one or can't find the one I have bought!