I was reading about Dex-Cool today and the many reports out there of its evil effects. Having experienced this first hand, I thought I would post up some pictures. Dex-Cool resulted in the demise of my radiator, the blockage of my heater core, I ended up replacing the water pump trying to figure out the unusual heating of the engine (never over heated, just never cooled right).
I eventually installed a coolant filter to get the residual stuff out, switched to green all makes and models coolant and havent looked back.
In trying to figure out what was blocking my radiator, I tried draining it to see what would come out. So plugged was it that even with the drain plug fully open and out, it would only drizzle out. I pulled the upper hose and sucked out coolant with a fluid extractor. Below is some of the sediment that I got out. It is Dex Cool sludge that has hardened and settled to the bottom of the radiator and eventually partially plugged it.
Another View:
In an attempt to save my radiator, hoping that the Dex Sand, as I call it, would get stirred up enough that I could trap it, I installed a coolant filter to try and catch all the gunk. Below is a picture of what I caught with the filter after just 5 minutes of running the engine.
It wasnt a couple weeks later the radiator finally gave up and I had to replace it. I had to clean the filter everyday after driving to and from work until the radiator failed and was replaced.
Below is a picture of my coolant filter. Its actually on backwards in the picture and I had to turn it around so that the U part of the screen faced the coolant flow from the engine. That screen would be about 40% full of Dex Sand, along with all the sediment trap caught (pictured above) and as I stated required daily cleaning.
After I changed out the radiator and installed green coolant, it was still another month before I got the majority of what remained out of the system. Now I can go a month or two before having to clean the filter and even then its minor compared to what it was. All cooling systems produce debris (scale, calcium build up, etc) so its not a bad idea to have a filter on the system.
Think about it. They filter your fuel, your oil, your air, why not the coolant?