I have just run across my 4th (this season) very expensive chain saw to come into my shop for repairs with the engine $hot. The reason? It was never cleaned. Very few realize that after cutting "any" organic material, and if not cleaned, as the organic material decomposes, the acids that decomposition produces will eat into steel and aluminum. This very expensive Stihl CS had a hole that was in the crankcase just behind the clutch. You can actually see the acid erosion. This is more common when cutting Yucca which has a higher content of acid. On mowers you can "rarely" see paint under the decks after a season. It pays to keep clean, if not for appearence, at least for durability and longevity.