Five mechanics say there's no problem with head, one mechanic said head needs to be repaired. Car not over heating, no or very heat, do add a very small amount of coolant at times. I'll drive car, let it sit for a half hour, check coolant and it's still under pressure and went everywhere. Temp, gauge works.One garage put in stop leak, now there's black stuff all over radiator cap and floating on top of radiator. Am going to have someone change thermostat, had 2 put in with in 6 months, change fluid and put on new radiator cap this week. What should I do, a lot of money put into this car. Roughly 220,00 miles on her, besides this she runs great!

 

Wuts the exact issue. ?

 

so ... you have a slow loss of coolant, but everything works fine?

 

I had a similar issue after an engine and radiator replacement. I traced it to either the overflow hose being loose at the radiator connection, or the radiator cap. When I removed the radiator cap, I noticed that the gasket was not nice and flat. It had gotten bunched up somehow. At the same time I got the gasket straightened out, I also cut off a piece of the overflow hose that was stretched out from being on the overflow stub for 15 years. You could also use some kind of clamp or zip tie to keep the hose tight on there. One or both of those things fixed my leak.