I'll tell you that changing the oil on my 2000 Yamaha WR400F is a pain in the a$$! I took the oil strainer off and cleaned it and put it back on and oil leaked from the bolt on the oil strainer because the copper gasket has scratches and cuts on it! I bought a copper gasket almost like it and put it on but apparently the gasket did not seal because it was a hair bigger. So i'll either have to order a new copper gasket for $2.06, go to a dealership and see if they have one or if they can order one. I've went to all of the auto parts store in my area and they don't have it! Has anybody had problems with any copper gaskets or any o-rings leaking? It's a pain in the a$$!