James, don't run the bus without getting it to operating temperature before shut down, period!

If you must do something to minimize the risk of the premature wear Kevin experienced, assuming you don't already have it, switch your engine over to synthetic oil. It has several benefits over mineral oil and will possibly retard the drying of the oil from the moving parts during extended periods of non use.
It has been said about synthetic oil, that engines running with synthetic oil, have had failures in their oil supply and lost all their oil pressure and were still driven to safety only to have no ill effects when that problem was corrected and new/more was oil added.

Synthetic does cost more, but not prohibitively so and it has been proven to excel over regular mineral oil. With it you should also be able to extend your change intervals and bring it closer to the cost you now relate to an oil change.



JIM