What coolant for a 4.3

[Ram@Will]

Hi everyone, I have a 2004 Silverado 1500 4.3 V6 5 speed, 40,000 miles and the coolant is al bit dark and i would like to flush it out. What coolant shou;d i use, the prestone premix dexcool or the Zerex dexcool formula ? i'm a tech and have seen some gm cooling systems sludged up,but i think its mainly from people mixing in other coolant types. thanks.

 

[MGregoir]

Flush the whole system clear, and change to Zerex G-05 when the system is completely flushed of the Dex-Cool.

The issue with Dex-Cool is it reacts with air and sludges, and has poor compatibility with gaskets. G-05 is a much better coolant, but you must completely flush the system before switching from Dex-Cool to G-05.

You can mix regular green with Dex-Cool safely, but I do not know of ofther types.

 

[ZGRider]

Ram:

Yeah, the factory fill (Dexcool) turns brown because it is starting to sludge up. If you let it go, it will get a whole lot worse. Get that stuff outta there and put some decent antifreeze in your GM. I second the G-05 recommendation. You could use Mopar antifreeze and it's the same color as Dexcool but is G-05. I changed my '06 Silverado to Mopar antifreeze right after buying it.
Just goes to show that Dexcool and GM haven't changed the formulation. And GM hasn't cured the intake manifold gasket problems