Thermostat? Heater core? I don't know. But I was driving down the highway when my 2008 Legacy Outback made a rattling sound. As I pulled off onto an exit, I lost power and smoke began pouring out of the engine. There was still fluid in the radiator although some of it had sprayed from under the cap. The mechanic said the engine overheated and blew. He offered to get me a used engine for $3500. I may not be the smartest girl on the block, but this doesn't sound right to me. It's had good upkeep and is a four-cylinder with 129,000 miles. Any thoughts from the Subaru savvy out there? Much appreciated!