I changed the oil in my 420 this past weekend . Put in synthetic . I also did a 350 as well . I went to a bike shop and bought the filters for these bikes . When I got to changing the filters , the one for the 350 was right , but the one for the 420 , was to small . The shop guy looked on his computer and said both bikes took the same filter , but thats not the case . Anyone know the part number for the right filter for this bike ? Its an ’09 420 , fuel injected , 4×4 , independent rear suspension , electric shift . Thanks for your help .