Mark

the 2.1 engines with over 130k miles have issues with the big end of the rod distorting and throwing rods one of the symtoms is low oil pressure at warm idle. http://www.bostonengine.com/articles/low-oil-pressure.htm doing 80 with an older 2.1 is not recomended I would say that 70 is the max sustained speed for a van engine. That is 4000 RPM its about the same std and auto trany.The WBX engines I have taken apart over the years have some comon problems exhaust valve seats that are pounded is one I think to much sustained RPM is one reason for this.  

Bob

Mark wrote 
 I was driving down Interstate 5 heading due south, going about 80 mph, saw
a gas station, decided to exit when at that moment the buzzer went on. Water
temperature wasn't higher than the top of the led itself. I turned the
engine off, and coasted down the road, into the denny's parking lot next to
the gas station. Let it cool, let my mind run wild. Added more than half of
a bottle of gunk. Wasn't low on any fluids. After a few hours, I started, it
ran, and I drove 60/65 mph all the way to Riverside. No problems since then.
Thinking is, oil got hot which made it thin out which caused the oil
pressure to drop. It wasn't that hot that day. Is this just a day in the
life, or is it an omen?