I replaced my water pump in the 2.8L Firebird recently with the Autozone "Duralast New Water pump" - Specifically:

I put in what I *thought* was "Extended Life Antifreeze". It was Prestone in a yellow jug:

http://www.prestone.com/products/antifreezeCoolant.php

It's the top yellow jug - "Prestone Extended Life Antifreeze/Coolant".

I wonder if the "Extended Life Antifreeze" referred to in the sheet in the box, (and on the AZ website) is Dexcool. Would Dexcool have any other effects besides the anti-corrosion stuff I read about? I don't think the prestone extended life "compatible with all antifreezes" is Dexcool is it?

Specifically I have this odd chatter at idle (and a little above idle), that comes and goes and sounds vaguely familiar (but not the same as) to the sound the old pump made when the bearing wore out.

Its not unlike a loud computer hard drive, mid-pitched, squeaky, intermittent, does not vary much (other than going away completely) at higher RPM. It also changes as I turn the wheel, but I ruled out a power steering pump bearing by swapping in another power steering pump I had. Same noise.

My friend told me it may be the new water pump needing dexcool for the seal, but I don't know how much I'd put on that. coolant is coolant right?

Tensioner perhaps? I sure can't pin it down very much.

 

Dexcool is compatible with nothing but dexcool! and it usually isnt good for the 100,000 miles! Prestone extended life is better , but you must flush the whole system and then put it in. The make also an extended life that is universal and can be mixed with other stuff and is yellow. We use it all the time with good results. To find the noise you may need a mechanics stethescope, you can really isolate noises well with these. Just some thoughts from someone who unfortunately has to do this every day for a living.