When I was a kid my parents used to buy Murray mowers and the decks would rust off long before the motor ever died. They would clean off the grass after every mow. That said I bought a Murray when I got married 14 years ago, I paid like a $100 for it, I seldom cleaned the deck and I still got the mower and it is solid as a brick. I bought a Lawnboy, 5 years ago, because Iam a 2 stroke nut, and wanted to get a new one before they quit making them, I clean it out about every third cut and it has no rust. My conclusion is, that they use alot better steel now or better treated, I should say. When is the last time you saw a car seriously rust out like you used to see in the 70s, its rare. If it makes you feel good, Id give it a shot of WD40, after you clean out the grass every week, but I feel you have nothing to worry about. They dont rust out like they used to.