Cav is not the only problem that tractors suffer. Lack of regular coolant changes also cause problems. Water pumps, cylinder walls, etc.
One can check the condition of the coolant by measuring with a digital volt meter. Once the coolant reaches 0.4v (DC) it's time to replace it.
It gains voltage because it breaks down; creating acidic solution, which in turn causes the difference in materials (coolant, iron, aluminum) to create voltage like a battery.
0.2-0.4 is considered normal. Above 0.4, time to replace it. It was explained to me that the same principle applies to Ford trucks, dodges, and about everything else. Main problem, however, is that the voltage may differ a little because of material differences, say, like on a VT365 where the cylinder heads are aluminum. I don't know of many kubota's using aluminum cylinder head. Not yet, anyway.