hello , my mower is 5 yrs old . it is well taken care of. now just started loosing 1/2 qt. of oil every 2 hours of operating.never had any problems before . cant see any oil leaking . don't smoke.no strange noises. just loosing the 1/2 qt oil every 2 hrs. now my local kobota center wants to tare down engine and look at rings . my thought is may be something like pcv . is that posible on this mower? any help would be great . not quit ready to let engine be completly torn down yet .what do you all think ?