hi,
I brought some G12 to a shop and flushed my coolant 2 days ago. Now I found the coolant in my car is green. Is that because the shop did not flush the coolant completely and mixed the G12 with old coolant? Should I bring my car back immediately?

btw, I found the oil temp. needle will drop from 1/2 to 1/4 after a long run, but sometimes it will go back to 1/2. What's the problem there?