ORIGINAL: Ram Jet
Early anitfreeze was bad for any metal. My father told me a story about when he put a 1939 Ford up for storage while he was overseas and filled the cooling system with antifreeze he pilfered from a Curtiss P-40 hanger. He returned to a pretty much dissolved radiator. Against every thinking mind set on the freeworld, I remove the 50/50 water antifreeze from all of my cars and run pure antifreeze. It will destroy cooling system parts if not changed? Baloney. I did that with a 1985 Nissan Sentra and I never touched any cooling system componet with 240,000 miles on the clock. Hence PERMANENT antifreeze. It's your money.
Bill
No offense intended, but ethylene glycol was introduced in the mid 20's and it was called "permanent antifreeze" because it was to be used year round as it offered the added benefit of a higher boiling point which keeps pressure down within the system even on a hot day... if you remember cartoons featuring early cars and radiator caps blowing off the top of the radiator... that was a reality back in the very early automotive days. You should run a 50/50 mix with water because it vastly improves the heat transfer of the liquid and doesn't significantly increase the freezing temperature. And I'm sure you can get away with a couple hundred thousand miles running the same coolant, but why would you want to seriously? It's not that expensive and if you're a real miser it's not a very difficult proceedure, it might cost you $10-$15 to flush the system yourself... you should do it every 100k miles at least to keep the efficiency of the system intact.