there is nothing wrong with dexcool. its one of the best coolants out there. the problem lies in GM's initial gasket design. they were being eaten up by the dexcool. just change the lim gaskets to the new design and you will have no more worries.
I just flushed my brakes and Coolant...I was just wondering on my pressure cap there was a little bit of a brown slimy gunk.. Someone that lives here claimed it was a lubricant.. Uhhm I may be wromg but I think hes kinda retarded anyway, its not foamy and my oil is completely fine along with my coolant Im guessing its just a buildup or rust or just gunk associated with the coolant system.. anyway I had the dex-cool in it then When I got the new (used) motor installed I guess the mechanic decided to go ahed an use the green stuff... should I just stick to the green stuff or you think its smart to switch back to the dex cool?????????
From the factory, the Dex-Cool systems come with a bit of stop-leak already in the radiator. That is most likely what you are seeing under your cap. I wouldn't worry too much about it, if you coolant and oil look fine otherwise. Just clean off the cap, and see how long it takes for it to come back. You could also probably take out your coolant reservoir and clean it out, too, if it has the rust colored build up in it.
As for the green stuff vs Dex-Cool, as long as all the Dex-Cool was entirely flushed out of the system before the green stuff was introduced, you will be fine. The green stuff will just need a little more maintenance than the Dex-Cool should.