From experience in the older days with gasoline engines where they were underpowered or lets say they were close to maxed out with empty rigs. Then there were heat issues which is a big killer of engine longevity. Usually cracked exhaust manifolds were common along with quickly failing spark plug wires.
Granted the newer fuel injected engines of today are much better but again I would guess by the time a motorhome is loaded and ready for travel it is way maxed out. Then like previously stated are the RPM'S the engines are turning with the 4:56 gearing in the differentials, which it needed to get the thing moving down the road. So with all this said it is understandable why they need careful inspection in the 60K range even with good maintenance.
Good luck in buying many good older motorhomes with low mileage. Lack of use is just as harmful to all the components as well...Just find a good trustworthy mechanic if one is available to go over the mechanicals before spending a dime.
