From reading the other thread on the Ranger forum it sounded like a dirt ingestion problem, that's why I recommended the Donaldson air cleaner. That was before I'd heard of these engine failures on the Brutus. It seems there is more to this than dirt ingestion, may be a design problem with the engine. The Kohler Diesel isn't totally new, it's a Lombardini design that's been around for a while. I don't think it was originally intended for vehicle use, and it must have undergone some recent changes to meet Tier 4 final emissions. There's at least one other UTV manufacturer using the engine, I wonder if they are having problems.
Knowing Polaris' reputation handling warranty claims I feel sorry for everyone who got stuck with the Kohler.