Pics of the rod bearing surfaces....
remove the oil pump and look at the rotor and clover gear...Take a pic...
Pic of the cam lobes (metal in the oil after only 3 hrs) Kohler had some cam issues a few years back , the cam lobe would wear down and fill the oil with metal.
Pics of anything that doesnt look clean and new.
It sounds like alot of work , But , you might just get it warranteed .
Parts dont lie.....People do..