Book says to change every 12,000 miles,checked with the dealer and respose was "it's as expensive as a full service" wow 850.to 1100. $.So 60.00 for a K&N filter,approx.time 4 hours to accomplish the deed and I was done.Down side,at 210000 miles it didn't even look dirty.By my calculations the dealer wanted 250.00 to 300.00 per hour.I know we hve to support the dealer network,but come on guys,we are riders not Dot Com millionaires.