Tan Slime in coolant of T/A

I have a 2000 T/A w/ automatic tranny and about 20,000 miles on it. When I was checking the fluid levels the other day I happened to notice that the coolant dipstick was covered with a tan colored slime. The
level was fine, but what the heck is causing this? Is my radiator or engine block corroding? The oil looks fine and I've been using Mobil 1 10w-30, changed every 3000 mi. since I bought it new, but the coolant hasn't been changed yet. I thought this stuff was supoosed to be good for 5 years. I'm going to get a coolant change and flush asap, but has any damage been done to my car? Is this so-called long-life coolant not as good as advertised? Is there something else wrong with my beloved Trans/Am? I thought It would at least be good for 3 years. WTF? TIA for your input.
Brian, Houston, Texas
2000 T/A College Student That's Too broke to afford mods except for SLP Lid and Power Shot Air Filtler
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Change Dexcool like you would the green stuff, at least every two years. also make sure the radiator is full. any air in the system reacts to form the slime you describe. When it came out it was sold as a 5 year 100,000 mile coolant, it was wishful thinking! Greg

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I had the same slime in my reservoir when I bought my 88 GTA, but I haven't had any coolant probs. I just cleaned out the reservoir and changed the a/f. ;
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Check your Transmission fluid as well to see if it's low, if you have a bad Transmission Cooler in the Radiator it will leave a reddish/brown scum in the Radiator Coolant. You won't notice anything to indicate anti-freeze in the transmission on the dip stick, only a low level of fluid. If you find thats the case, change your Radiator.
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