I have a JD8850 that has a small amount of water in the oil when the tractor is stationary overnight. When it is running, it uses the water but does not go into the oil. I have heard that it could be a leak through the intercooler when it is running and the leak past the water pump gasket when it sits down.
We have had some who have done it, one we have solved with cylinder head gaskets, others we have ended up reviewing. It seems like most of the time it’s the O-rings on the bottom of the sleeves. We have reused the sleeves and pistons, they have been disassembled as a unit so we have not had to put rings.
John Deere has used the engine as a structural member since the new generation 10 series in the early 60’s. That’s why they have that damn heavy cast iron pan and not a light steel one. they also work the pan gasket with dozer blades on them, think about that senerium for a moment. The engine frame rails are lightweight and the crankcase is cast iron. I guess for the most part it worked, but I don’t like the idea or the pan fight back there.