I would love to hear the science behind how it would effect the operating temp of a radiator when you go up in elevation...ask him for me.

Altitude changes the boiling point of liquids due to the lower atmoshperic pressure. This means that the coolant will begin to exert pressure at a lower temp, but the cap should not be venting (much if any) until you are at a point the car is beginning to overheat. Remember, our pressure caps are on the res, not the radiator.

More likely than not the temp difference is due to the temp compensating board which I am about 99% sure your 93 has and your 84 may not. Of course, I foolishly do not know what 1/8, 1/4 or 1/2 means but I assume that you are talking about the middle of the 180 degree swing when you say 1/2. Your might also have a different radiator configuration (2-row, 3-row, brass, aluminum) or the older radiator may just have more deposits in it leading to slightly higher temperatures. Also, automatic or manual tranny in the 84 vs. the 93. Which thermostat in each?

Too many variables.

Onkel Udo