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Years ago I decided to drive a Brat from Wyoming to Indiana. It started losing coolant climbing the Bighorns. I kept on driving. By the time I left Wyoming their was no coolant in the system. It didn't seem to effect the performance. l finished the trip and drove it for a month or two before I found some heads, had them rebuilt and installed them. It never seemed to suffer any adverse effects.
Will any of the newer Subarus do that? I just bought a 1999 Subaru Legacy 2.5. Something tells me I would be pushing the limits to try running it out of coolant.