Pontiac Repair: Coolant leak 1999 Pontiac Trans Am Convertible, coolant recovery, coolant leak

Question
Car is a 5.7 liter SFI/AIR/EGR/TWC/HO2S automatic trans, AC. It doesn't leak all the time and never in the garage. The one time I saw it leak it was coming from the passenger side front, around the coolant recovery tank. Cooling system has been pressure tested several times and it never shows a leak this way. The cooling system calls for the GM reddish/orange coolant, when I bought it in 2005 coolant was green and I refilled it with green antifreeze for 2 years until I had spent a lot on it and finally read my owners manual. Dealerships missed this too, green coolant I was using was not the universal-type. My visual inspection of leak that one time found no wet spot I could reach or see. It has never leaked more coolant than the top tank area of the radiator. Any thoughts you may have would be appreciated...thank you.

Answer
Hey Doug:

well my first though is a water pump leaking. It could be the radiator too being wehere you said it was. The most common leak on that engine is the water pump and usually they leak only when they are cold at first and as the leak gets worse they will leak when it's hot as well. I would suggest have it pressure tested after it has sat and it cold. You can alos add a tracer dye to the coolant and then with the use of a black light find hard to find leaks easily. as far as green coolant VS red no they don't mix well but you can keep the green stuff in there you just need to have it chnaged every 2 years the dex cool is good for 5 years 1000,000 miles. even if you swithc it back to the dex you still will need to flush it due to the fact that the two were mixed and you will never get all of the green coolant out of the system. Good luck.