The title says it all--How many hours do you get out of a commercial mower (ZTR) before you sell/dump/trade it in?? Is it gas/diesel?? Is it worth it to you guys to spend the extra $$$ for the diesel engine?? FYI I typically sell mine every two years. The last one I had I sold when it was two years and one day old. Main reason: Warranty! I got really burned on my previous mower (2 mowers ago). I had to replace the engine (Kawasaki), and BOTH hydralic pumps!! Luckily the engine went out a month out of warranty and they (Kawasaki) replaced it and I just paid for labor to install it. But the pumps costed me a pretty nickel! Just wondering what you guys do-do you run them into the ground until the tires fall off? or trade/sell them every certain amount of time?