Here is a story that happened to me a couple weeks ago... Its just getting warm here in the SE South Dakota / SW Minnesota area. My riding crew (brother and friend) and I were invited to the track that we usually ride at during the warm months. It was getting up to around 50 degrees that day (pretty warm for first part of April) making us eager to ride. We got to the track and the owners son (who shall remain nameless) comes up to the truck and asks us how to change the oil filter on his 2007 YZ450F. Come to find out no one had never ever changed the oil filter all the time he has had the bike. He bought it new in the end of 2006! The story gets better! He has only changed his oil 2 times the whole time he has had the bike. He rides the bike ALOT; almost everyday since he has the track on his farm and he is home schooled. We where amazed! The filter looked black, the oil looked like sludge. Later we found out that he still had the original air filter on the bike. It was never cleaned or oiled in all the time he has had it. The bike runs as strong as any 450 should and had never given him any mechanical problems. This kid doesn't know anything about maintenance, but this story does have a bright spot! I am confident with my maintenance schedule my bike will last at least 20 years! I would never ever recommend anyone to do this to their bike, but it is a testament to how well YZ450Fs are made.