452 hours on a non commercial Brigs engine is far beyond what I saw on my last 2 Craftsman mowers that had v-twin brigs in them. I use good (Amsoil) lubricants in mine to try to help them live, but I just couldn't get 4 full summers from those 2 engines. I have 6 years (almost a 7th under the belt) on this 2010 Craftsman with the Kohler. Your doing good, I would guess I had 300-350 hours on the 2 Brigs engines when they were finished. It was a shame because my frames/decks were still in very good condition with only minor paint missing and slight surface rust in places. The machines were no where near done physically... but yet with the death of the hydro units and the engines using as much oil as gas.... The good thing is that the engines were done and the hydro units were done at about the same time. Mine would be smoking like a old coal train by the time the hydro completely took a dump on me. This new one, the engine is still running at 110% and the hydro is starting to slow down on me... the end is coming. But it's done a valiant job for just under 600 hours now. I guess it doesn't owe me anything for the $2600 I paid to get 7 full summers.