GM antifreeze - orange?????

Dex-Cool has a different formulation than older antifreezes, but it's still ethylene glycol. If you mix it with a standard antifreeze, you lose the extended life benefits.

If you google on "Dex-cool", you'll find a number of sites saying all kinds of terrible things about Dex-Cool. The fact is, about the same time GM switched to Dex-Cool, they were having serious intake manifold gasket problems with their 3.1 and 3.4 liter V-6 engines. Dex-cool got a bad rap as a result.

The intake manifold gasket is a plastic form with a silicon seal molded into it. The system is designed so that the plastic will set the preload on the sealing part.

I found out two things the hard way. Don't torque it down as the torque is about where the plastic meets the metal and another bump on the wrench (don't have the manual in front of me). Secondly, looking at the OEM and after market, there is definitely a quality problem with the molding on the OEM. At least on mine anyway.

Worked on cars all my life but to fix this sucker, I had to essentially lift up and prop up the maze of sensor harness and slide the manifold out from under. Must have disconnected 25 sensors. A real beast and the car had 45000 miles.

Don't blame the antifreeze on this one. Silicon is resistant to EG, heat, and lots of things except it swells when subjected to it'self (Dow 300 Silicon Oil. Not a lube, a dielectric insulator/coolant).

txblu