Most of this conversation is concentrating on what is best for the engine. But we are talking about the tractor, not just the engine. Anything with hydraulics and power steering will have the same pumps and issues. Hydro or shuttle, my little tractor has about 8-9 gallons of cold, thick non-synthetic hydro fluid that needs to be moved and warmed before really cranking up the throttle much. Doesn't matter if the engine is warm, the hydro still needs to be warmed up too. My lowest throttle setting is around 1100 rpm. It has no problem getting the engine up to operating temps at near the lowest setting. The temp gage says it's getting plenty warm. My truck on the other hand idles at just 680. It can not get up to operating temp at low idle. But high idle is only about 1100. No where near half throttle.