Took my Ford Focus to have it pressure
checked for a coolant leak and have the system flushed. Cost me $70, but I thought they could find the slow leak. They said there was no leak. Next day, while changing the oil, I did notice a small leak coming from the thermostat housing. I replaced the housing myself, but I had to drain much of the new fluid first!
I am not a professional ,and they are supposed to be; yet, they failed miserably in checking it out properly.