The guys there gave me some free coolant but they were right, this had nothing to do with the oil change. It was sunday so I just drove home. well, bought some coolant on the way, then drove home. then this morning I refilled it and drove to a dealership, where they replaced two hoses and a cracked housing, and re-did my brakes while they were at it because I was way overdue for that.
I had time to kill when I got off work and had to pick up my car, so I walked around and looked at new ones and thought about how easy life would be if I just had predictable car payments every month instead of surprise car maintenance. my poor poor credit cards.