Coolant Change 05

[cyellowvette]

Anybody tell me the correct way to change the coolant in a 05 C6? Also what should I put back into car, Dex Cool or change to something else? Thx.

[catbert]

I change hoses and thermostat when I change coolant - makes it real easy. I pull the bottom hose loos and let it drain into a catch pan. Then you can take off the top hose at the t-stat housing or take it off as a unit. It really isn't a tough job. As for the replacement coolant - everyone has something to say about that. Do a search.

[Hib Halverson]

The LS7 is like other Gen 3/4 engines in that you can really "change" the coolant because the block drains are not accessible, well...not easily accessible.

The next best thing is to do like "Catbert" says but then, fill the engine with tap water, run it for a while, drain again, refill with water a second time, run it for a while then drain a third time.

After you've drained out all you can get, refill with your coolant mix. You have to guess how much water is left in the system then add Dexcool according to the coolant mix you desire. You also can test the antifreeze concentration but the tool necessary to accurately do that is a bit pricey. It's called a refractometer and is available form SPX Kent-Moore.

Cheap hydrometers are also available from auto parts vendors but several years ago, in the process of doing a review of these devices, I bought four different ones and each one read differently. My assumption was that none of them were accurate and the Kent-Moore refractometer was the only good tool to use to accurately measure our antifreeze concentration.

What do I use in my engines?

In all but one, I use straight distilled water and Red Line Water Wetter. Obviously, living on SoCal my engines don't see freezing temps so I take the better cooling of straight water in exchange for the freeze protection. Also...straight water is much more maintenance intensive. It needs to be changed every two years/24,000 miles.

Obviously, a 50/50 mix of Dexcool and water can be run a lot farther.

[cyellowvette]

The LS7 is like other Gen 3/4 engines in that you can really "change" the coolant because the block drains are not accessible, well...not easily accessible.

The next best thing is to do like "Catbert" says but then, fill the engine with tap water, run it for a while, drain again, refill with water a second time, run it for a while then drain a third time.

After you've drained out all you can get, refill with your coolant mix. You have to guess how much water is left in the system then add Dexcool according to the coolant mix you desire. You also can test the antifreeze concentration but the tool necessary to accurately do that is a bit pricey. It's called a refractometer and is available form SPX Kent-Moore.

Cheap hydrometers are also available from auto parts vendors but several years ago, in the process of doing a review of these devices, I bought four different ones and each one read differently. My assumption was that none of them were accurate and the Kent-Moore refractometer was the only good tool to use to accurately measure our antifreeze concentration.

What do I use in my engines?

In all but one, I use straight distilled water and Red Line Water Wetter. Obviously, living on SoCal my engines don't see freezing temps so I take the better cooling of straight water in exchange for the freeze protection. Also...straight water is much more maintenance intensive. It needs to be changed every two years/24,000 miles.

Obviously, a 50/50 mix of Dexcool and water can be run a lot farther.

Thx. for the info, i will flush it several times with water before I refill.