I hope that some of you can give me an education on lawn tractor hydro transmissions. Having grown up with gear transmissions on lawn tractors, I'm afraid I'm rather behind the times now that I'm considering buying. I have heard that hydro transmissions can not be serviced by the owner. Is that true? If so, and I'm assuming that a lawn tractor tranny is just about like any other - heat will break down the fluid, how reliable are they? How often do they need service? How can you tell if you can't even see the fluid on a dip stick? Do they overheat under a heavy load such as cutting in high grass/weeds? Do they "pull their weight" as well as a gear tranny? Which tractor brands are most reliable as far as the tranny goes? Any other related info would be great. Thanks