I have 2006 Chrysler 300C temp was going up garbage showed me thermostat filled with rust! Said Antifreeze suggested by Chrysler caused it.
Well, do a flush and use some Lubegard with new thermostat. If it continues then you know at least the head gaskets may be bad and then decide. Sure it was rust and not oil in coolant or exhaust in coolant? May be best to perform a compression test on all the cylinders to confirm the head gasket is good or bad before continuing.
Search Chrysler 300 Questions
Chrysler 300 Experts