The engine that is in your tractor (2403 series engine) in just about the same engine Bobcat uses in their skid steers. Those units get started and shut down without abandon all day everyday for years on end no cool down or anything of the sort. The rental company I work for has over 3,000 of these units(currently and over 10,000 sold in the last ten years) out of all of these units with an average of 2,000 - 3,000hrs on the clock when they are sold over the past 10 years we have in total replaced 3 turbos, 20 fuel injection units and 5 engines. I purchased a Kubota and more specifically the MX4700 (with the 2403 series engine) for this reason. This engine is probably by far the most reliable (even under abuse) engine in our fleets. For cool down you rarely need more than a few minutes for a turbo, for non turbo, your just wasting fuel letting it run more than a minute.