Changing thermostat in my Silverado

[MrRocket]

First time I've ventured off the Oldsmobile topic...:)

I'm wanting to change my t-stat. and the Dex-Cool in my 2006 Silverado. Going to go with Ethylene Glycol (old school antifreeze). I need to get the Dex-Cool all out since it doesn't mix with the old stuff. Any ideas on how to do this in the 5.3 (327) engine? One of my concerns is how to get it all out and put new antifreeze in with out trapping air in the system. There is no radiator cap or a radiator drain valve.

[jrsixx]

There's gotta be a petcock on that radiator. Other than that, pulling the lower rad hose, and flushing some water through, although you're never gonna get ALL of it out. Why are you going old school anyway, whats wrong with DexCool?

[73CS]

Don't do it. They go with the Dex-cool for a reason. At least go with the mix with anything version of the anti freeze. And if any Dex-Cool is left in the system it wont be affectrd like the old green stuff. I think it has to do with the aluminum in the new engines and radiators. The price difference isn't that much.

[MrRocket]

My mechanic told me that the Dex-Cool gets corrosive over time and that he has seen water pumps with the impellar eaten away plus other signs similar to that in engines with Dex-Cool in them. Suggested I change it and said if it were his truck he'd use the older type antifreeze. I've also heard of others having trouble with Dex-Cool, some say change it others say don't change it. I just want to be confident that my engine is safe and is not being slowly eaten away.

[zodiacblue442]

I like Oldsmobiles and I like GM trucks so I'll help. :p There should be a radiator drain plug with hose, and maybe a vent (can't remember exactly) on the driver's side of the radiator. At least there is on my dad's 00 Silverado, my 01 Sierra, and my brother's 03 Silverado. To change the thermostat (t-stat), the housing is combined with the water pump so you have to pull the water pump off the engine. It's not what I'd call fun, but I've done worse jobs. It should be easier on your truck because they changed the engine fan design in 05 I think. I had to pull the water pump on my Sierra because the seals between the pump and block were leaking.

In order to change from Dex-Cool to regular antifreeze, you would have to do a complete system flush. This means put a tap in line to a heater hose, or pull a heater hose loose and make the connection there if you don't want to splice in a flush tap. My thought is if you change the Dex-Cool every 5 or 6years, your engine will be fine. My Sierra has been running Dex-Cool since new. I've had it flushed/changed once about 4 years ago (the dealership did it when I had some work done at the end of the extended warranty). I pulled the water pump off just a few months ago to change the seals and I saw absolutely no evidence of corrosion. My dad is going to flush and convert to regular Prestone antifreeze in his Silverado this summer. It's still got the original coolant. His reason is the regular antifreeze is more readily available so it's just more of a convenience thing (and he likes "old school" stuff) instead of a concern related to corrosion. I've heard the corrosion concern with Dex-Cool and I'm not worried about it. Think of how many million GM vehicles were made and still on the road running just fine with Dex-Cool.

Lastly, regular antifreeze should be changed every 5 years also, including in our Cutlasses, whether driven 500 miles a year or 15,000 miles a year. The rust inhibitors break down over time which leads to internal corrosion concerns. Just another thing to remember as part of regular vehicle maintenance. Speaking of which, my 442 is about due again. Sigh.

Hope this helps.

[MrRocket]

Thanks for the replies everyone, I guess I'll give it some thought and wait awhile before I do anything. It's running fine now and it gets much better gas milage than my old Dakota.
I tend to like the old school stuff too most of the time. I don't really like not knowing how to do stuff on newer vehicles. I can do alot of the maint. on my Cutlass. It just seems like there is always something that makes it difficult on anything new. That's why I asked, just trying to avoid the usual surprises! :)
I've heard stories about Dex-Cool being bad for some time now but all GM people deny anything bad about it and claim it's all myth or paranoia and urban legend type stuff. I've even heard about a class action suit against GM because of Dex-Cool. Really don't know what to believe and I don't know if that's true or not, never did any research to see if it is or isn't.
Thanks again for the comments though much appreciated! :)

[zodiacblue442]

My dad sent me these links. For some reason, only certain six cylinder engines have a problem with Dex-Cool spanning from 1995-2004.

http://www.girardgibbs.com/Dex%20Settlement%20Press%20Release.pdf

http://www.girardgibbs.com/dexcool.html

[MrRocket]

Thank you for the links, I will read up on them. :)