Not changing ANY FILTER when recommended, to me, is like washing your face with a dirty wash rag. There just are no shortcuts worth taking with these lesser expensive maintanance items. I had an 86 300SDL tranny act up with erratic shifting patterns only to find out that the MB dealer I bought it from at 80,000 K had not changed the trans. fluid and filter and had indicated on the service record that he had. I had it properly done in Minneapolis which resulted in a full quart of the severely contaminated fluid ending up on the selling MB dealership manager's desk and the service manager trying to explain. You had to been there to see how pathetic this was. It cured the shifting problem and drove it another 40,000K without any further problems.