I might just as well chime in here. I have and have had upper tier JD riders. When it is damp or wet, I hose the decks out after every use. EVERY one. Sometimes I really push these mowers beyond their intended use, on a place like mine with moles and voles, ruts and nuts. tall and wet. Sometimes I have to do it half way through the mowing.
Later summer when it's dry to the bone, not always. But before I quit for the season I hose and or scrape the underside of the deck and spindle assemblies. My three point brush hog mower I do the same. My flail has duck feet and it balls up in tall green. I hose that out frequently.
I don't oil the undersides or treat them with anything, but I store all this stuff up off the ground and covered one way or another.
Back in the eighties I took a gig working for the local Parks Department during a timber downturn, survival job. After every day, back in the shop, we hosed out all the mowing devices, tractors, walk behinds, ZTR's , everything. It was the rule. It paid in dividends to keep the stuff cleaned out.
Decks with caked dirt and grass, don't operate as designed. It puts stress on the blades, deck, belts, pulleys', motor. It may be **** but it keeps stuff running as it should and easier to maintain a clean machine than a crusty one.
On of my best investments was a HF mower lift. Not German engineering, but it makes the deck cleaning EASY and complete. They are worth their weight in gold. A clean deck is a happy deck! anytime of year
