Once an engine reaches operating temperature, it goes into a "steady-state".
That is what the thermostat, fans, etc. are doing.  Granted, if you are
running it at extremes it may not do too well, but you will know that
quickly.  As long as the gauges stay within specs, you are OK.  If things
break on a long trip, they would have broken anyway -- just later on.

In theory, your van should be able to run continuously for 3000 miles.  Then
you have to change the oil.

Bill Marshall
'85 GL Tiico "Pandora"
Aurora, IL