I recently replaced the heater core in my 1985 F-250 (460) and as luck would have it the water pump went out the next week. Needless to say, I decided to flush the system and refill it with Prestone Extended Life coolant. After doing so, I have heard in conversation that extended life coolant "eats away" gaskets and actually does not extend the life of the coolant as expected.

Does anyone have any info on this? Should I flush it out and use regular green Prestone?

 

Usually Antifreeze lasts from 2 to 3 years in an engine under normal cooling/heating conditions...depending on how much of the rubber hoses are decaying from INSIDE the hoses. This is the stuff that is expected to happen anyway. IF your decaying hoses are old and you haven't done a flush in a while...you can expect that more of the same rubber decaying, rust from the engine block, and other material that comes from the "tap" water to make the antifreeze not last long. Thats why its recommended NOT to use tap water. use distilled water instead. Some water has iron in it while others doesn't ....still tap water is just that...its meant to drink as has other "safe" chemicals in it.
I done a antifreeze test several years ago, and found out that antifreeze will actually go bad in the same container..unopened. It lasted for 4 years in the container in a no heated invireoment on a concrete floor...it actually fuffed up the plastic container it was in. The stuff had turned to a slimey condition after eating away the inside of the container. ON another container that had use antifreeze, it was also slimy and brownish color. The antifeeze tester still tested good on the unused antifreeze and didn't on the tap water antifreeze.
My determination is to change the antifreeze every 4 years with a flush of the system with all new hoses....and then don't worry about heating - cooling problems.