2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 90Get this manual
CHANGING THE ENGINE OIL CHK ADJ
9If the oil filter element is also to be replaced, perform the following procedureaRemove the oil filter element cover and oil filter element 2bCheck the O-rings and replace them if they are cracked or damagedcInstall the new oil filter element and the oil filter element coverOil filter element cover bolt 10 Nm (1.0 kg, 7.2 ft lb)
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10.Check: engine oil drain bolt gasket Damage Replace11.Install: engine oil drain bolt (crankcase) (along with the gasket)