Forget the floating balls.
Read the manufactures recommendations on proper mixture of anti-freeze and H2O.
50/50 provides the highest boiling point and the lowest freezing temp.

A 50/50 mix protects down to -34* How much more do you need?

http://www.justanswer.com/questions/gxu3-undiluted-antifreeze-freeze

If you dig around, some sources show that using straight antifreeze (or less than 30% water) lets the coolant freeze (or gel) easier than using a mix.



Both the green stuff and orange Dexron III coolant are ethylene glycol type antifreeze.

From Larry's link:

"As the name implies the third main function of antifreeze is to protect the cooling system from freezing. The way to achieve maximum freeze protection differs between ethylene and propylene glycol. For ethylene glycol the maximum protection is at 67% ethylene glycol in water. A ethylene glycol solution of this concentration will freeze at -84° F (pure ethylene glycol freezes at 8° F)."

There are numerous opinions about what anti freeze should be used to replace the antifreeze in your 95-99 Riviera.
Below is a link to a thread that contains many of those opinions and a great amount of information regarding Dex cool and the traditional "green" antifreeze as well as the "mixes with anything" antifreeze that is also available:

http://rivperformance.editboard.com/care-maintenance-f8/gm-dexcool-coolant-antifreeze-t1364.htm?highlight=dexcool

Personally I buy the Dex cool concentrate and mix 50/50 with distilled water and use this mixture in our 99 Riviera.

Bert

When I have used a chemical cleaner when flushing, after I drain it out of the car I like to do another run with just water in the system to be sure I have it sufficiently rinsed out and neutralized.
I always get more gunk with that second run.

Then after I drain that, I add my fresh new coolant.

I also mix the coolant closer to maybe 60 or 70% since there will still be a certain amount of plain water in the block yet.
I figure once it all gets mixed together in the engine I am then closer to a 50% mix.

Nope, I think Propylene Glycol is the new stuff that's said to be less toxic than normal antifreeze. DexCool is Ethylene Glycol as far as I know.

Links:

http://www.getahelmet.com/jeeps/maint/dexcool/

http://chevelles.com/forums/showthread.php?t=64731

http://www.automotiveforums.com/t941573-dex_cool_and_malibus.html

I just did a radiator flush, surprisingly the tank and coolant itself had very little crud in it and when testing the old coolant, it rated almost as high as the new coolant I put in it in terms of hot and cold protection.

On a side not: I was tightening the radiator drain bung before filling the system and I thought I stripped it. I tightened a few too many turns and then it skipped. I took it out and inspected the plug and rad threads but didn't see any damage. I re-tightend and it squeezed down well, stopping one turn sooner then I did the last time. I ran the car for a while to top it up and didn't see a leak. Is it possible that it didn't strip because its plastic ?

Eldo wrote:

But since our engines are good ol' cast iron, and I hate changing gaskets, water pumps, etc, I converted to green upon the recommendation of my brother, who's been doing it for a lot of his customers at the shop...

What do you mean Eldo? because I was told that changing the coolant every five years with Dex-Cool would extend the life of the water pump?

_________________

Modern "Muscle"

1996 Supercharged Riviera, Black Cherry Ext., Burgundy Int., over 200K

The concern with Dex-Cool (orange) is that it deteriorates the lower intake manifold gaskets prematurely.
Some have had problems, others have not.
If the system is clean and all air (oxygen) is purged out then it appears to be safe.
From what I've read is that too much air or oxygen in the system will cause the Dex-Cool to become acidic or corrosive to certain types of gaskets. I don't know for sure on any of this data as there are more write ups in so many different places regarding Dex-Cool and it's ability to ruin gaskets that i don't know what is fact or fiction any more.
With all that said the regular Ethelyn Glycol (green stuff) can be used to replace the orange stuff if you have flushed the system completely and no orange remains, then use green coolant from then on and you won't have to worry about what Dex-Cool does to intake manifold gaskets.
Regarding the plastic drain plug, I think I did the same thing a couple of flushes ago and after removing the plug and inspecting it and finding no problem I re-installed as you did with no leaks or drips since then.
I would just keep an eye on it for a little while and if no drips then forget about it.

The main concerns about Dex-Cool are gaskets, plastic manifolds and gunk buildup. I added water pump just because the first new pump I put on my car lasted but 5,000 miles...

The link I included has more in-depth info, as well as some great pictures of orange gunk.

My car has almost 240,000km on it and I've never seen stuff like in those pics. Interesting link though Mark, its kinda scary. My fear now is that I bled the system OK, if the culprit is indeed air. I opened the bleeder screw on top of the the thermastat housing. I didn't see spitting, but rather a trickle, perhaps I didn't have it opened enough. I guess i will be checking out the tank now and then for any build up!

Thanks for the re-assurance on the overtightening Rick .

Let it warm up and try bleeding it again. Let fluid run out of the little hole for a while. It can't hurt.

One thing that would be easy to overlook or to not notice when servicing the radiator is to be sure and verify that the drain pipe inside the radiator overflow reservoir and the hose that goes from the reservoir to the radiator are not clogged. That little metal tube inside the overflow reservoir is easily clogged and it only takes a few minutes to remove and clean the reservoir. While you have it off check the hose to make sure its not clogged.

Bert

Bert makes a good point about the overflow tank system... That is what keeps the system "air-free".

As far as bleeding, I'm old-fashioned. Even sitting on flat ground, I don't think that in our chassis's the thermostat housing is the high point of the system. My memory's weak, but I think it WAS in the LeSabre/Park Ave bodies. Even if there's any doubt, I would just park the car pointing uphill, and let the air out the filler neck, while topping it off with coolant mix...