I use only 50/50 mix in my rad. Never heard of distilled water before. I will mention this to the tech next time I see him. I would replace the rad before getting rid of the Jeep anyway even though it can be a pain in the **** sometimes.

 

50/50
distilled water (available in 1 gallon jugs anywheres,[stores, gas stations])
antifreeze

 

I reccommend pulling a radiator from a 1993-1995 Jeep. They should be interchangeable... perhaps there is a manufacturing defect in the aftermarket replacements. Also like everyone else says do a flush... and do change the oil.

If you live in Florida (like I do) remove the thermostat. If you are consistently eating thermostats try a different mechanic who gets his parts from a different place. That might be blowing your radiators...I only changed my thermostat twice in my 1994 Cherokee from 94 to present with 210,000 miles... I usually get my parts from Napa, and never had any problems.