There are a number of graphite and silicone-based products around. TSC sells one called EZ-Glide which is graphite based and designed to be sprayed under mower decks, harvesters, etc. The problem is basically the longevity of the coating, or more correctly, the lack thereof. Me thinks EZ-Glide lasts longer in environments where stuff slides over, such as a harvester chute. Under a mower deck with tip speeds in excess of 17k ft/min, I was hard pressed to see any residual EZ-Glide after a single mowing. Others on the Forum have attested to this as well as an exercise in futility. Most folks reason that it's better to clean the underdeck with a good hose stream after each mowing, like Moss Road has described.
I think more important is grass accumulation under the two cover boxes on top. These boxes cover the pulleys (4) and belts. About every 4 mowings or so, I remove the bolts and wash everything with a strong stream of water. I don't have a pressure washer, but that would do fine, too. I wipe up the puddles of water in the pulleys, and grease the 3 Zerks (under the deck) for each of the blade spindles. Like FOURTEEN, I use a synthetic lube on these fittings
click here. The issue is not so much what grease one uses, but doing it frequently and often /forums/images/graemlins/laugh.gifThe pulley controlling belt tension has no Zerk. I discussed this in an earlier thread, and Moss Road indicated that this is a sealed bearing unit. I don't spray any coatings here as they tend to attract dust/debris on the next mowing. Just let it dry naturally, and replace the covers. No "belt dressing" either. Grandpa was right, I think. It just swells the rubber and hastens deterioration. I do use a "Never-Seize" dabbed on the cover bolts before replacing them. That makes it easy to remove them next time and keeps rust in check.
Hope that helps...