Hey Captain. Just so happens, I ask a guy ,whom's opinion I respect very much ,the same question. He knows me well and shoots straight. . He is an expert tractor mechanic and works only on tractors. In fact , he was the main guy at JD till he got his own very successful repair business. Anyway, he told me 10,000m hrs with a quality maintance program before any major overhaul.. He is only talking about the general engine and not the RTV specifically. I was concerned about my heavy use and being able to save up to buy another. so any way that is what he told me. I try to change the oil and filter about every 100 hrs which can get expensive up front for my frequent use. I change the trans every 400 hrs and I use all Kubota filters. Is that a Miller bobcat welder or a bobcat as in skid steer.? p.s.. I have almost zero blow by-- still. If this is a skid steer, There are other things to look at........... Bordercollie</p>