Distilled or Deionized water for coolant

[PaulTWinterton]

14 minutes ago, TobyB said:

The old pumps wanted a bit of lube.  I wonder if a modern one cares, or just uses well- sealed bearings...

 

I hate to admit that I only used water. Car is parked indoors so I didn't think I needed sub-zero coolant.  I went through 2 water pumps  in the 2 years that I had only water in the system.  About 5 years ago.  Both had bearing failure.  I used 50/50 before and after that time.  It seemed obvious at the time, but it's still only a theory.