Well, they're not true Kubotas, but the engine are pure Kubota. I'm talking about my Grasshopper ZTR mowers. My 1999 928 (28 hp Kubota diesel) has 1612 hours on it and still runs perfectly with absolutely no oil use between changes. Heck, it really doesn't even get the oil all that dirty in 100 hours to be honest.
One good thing about this is that I'm pretty certain that particular mower has found a new home. Since I don't do any commercial mowing anymore I don't need all these mowers. I will still have a '01 Grasshopper with a 21 hp Kubota diesel with around 780 hours on it and an '06 Grasshopper with a 22 hp Kubota engine on it with 110 hours on it. Just like the 28 hp Kubota, neither of the smaller hp Kubota diesels show any signs of wear, reduced power or oil consumption.
As a quick plug for Kubota and Grasshopper mowers, I've had absolutely nothing break in over 2500 combined hours on any of them. Whatever pumps are used in the "Gemini" series Grasshoppers are brutally tough just like the Kubota engines. Now that I think about it, the 28 hp Kubota mower even still has the original deck belt on it!
Oh yeah, I do have yet another 3 cyl. small Kubota diesel! My RTV1100 has a 25 hp Kubota diesel in it as well. It only has 17 hours on it though.

I'll be plenty happy if the engine and transmission on it prove to be as tough and dependable as the old Grasshopper Kubota!