WR450 black oily film inside engine??

Hi all,

During a recent rebuild of my WR450's bottom end due to a cracked crank case i noticed alot of black oily film coating all of the inside parts of the engine, more noticeable on the case's, head and rocker cover. I use motul ester 10w 50 and change it very regulary. Is it possible that its due to a clutch on the way out (which i havent changed in it since new, but isn't slipping), due to blow bye/fuel contaminating the oil or the particular oil im using?


Hot metal constantly in hot oil is the issue. Does not matter what you use a motor internals will "stain up". Those nice white metal shot peaned crank and crank rods you see advertised will be black in no time. Don't change anything but check your clutch simply because of use.

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