A clean engine is a happy engine!

camperdave wrote:
My two daily drivers are 15 and 20 years old, both with well over 100k miles. Neither ever gets washed, and I've never cleaned either engine (unless you count washing off mud/dirt prior to repairing something).

I guess I'm the exception to the rule about clean cars and good maintenance. My cars are filthy and pretty beat looking with plenty of dents and some rust. But they are very well maintained and I'd take either cross country tomorrow.

Exactly! How it looks on the outside is not necessarily a reflection of how it looks inside. All my vehicles are well maintained, but introducing unnecessary moisture into the engine bay isn't something I'll do. If an engine is well maintained about the only dirt on the engine is going to be road dust. A well maintained engine won't be covered with oil that needs to be cleaned. If you live on a gravel/dirt road, all bets are off.