When I bought my 3520 I got my dealer to throw in everything needed for 50 hr service. The oil filter he gave me is part#M806419. The manual calls for M811332. The one he gave me is shorter than what came from the factory. It looks like it will fit, but it is shorter. I called them and they said the one they gave is the one I should use. They said they know it is a different size but it is the one to use. I dont like the idea of using a filter other than the one specified in the manual, especially if it is a smaller filter. What do you guys think?