Exact Antifreeze Brand

[TommyL]

If the vehicle is driven in summer months only a 50/50 raitio is not needed...infact less antifreeze is better for cooling. A 50/50 raitio is recommended for cold weather driving but less antifreeze is recommended for summer cooling and lubrication of the pump.....less antifreeze and more water = better cooling. I use a 50/50 mixture beacuse you are correct in that some water will still be in the block so the end mixture is likely about 40/60.

[scottfab]

Oh boy, this is great. An actual dealer that will corroborate the story of head gasket failure due to or “connected with” Dexcool. Can I get the name of the dealer? I won’t mention where I heard it just confirm the issue with the 4.6 V6. The dealer is in Ontario?
I just want to nail this down so that I might convert back to the green stuff. Or if the issue is still related to the nylon/Silicone type gaskets then I will report on that.

[DMark]

This is the reason I won't use Dexcool......

Back when GM began to use Dexcool in LT1s back in the mid 90s, FBody & Impala SS owners started to notice that our heaters wouldn't work.

Turns out the "stuff" in Dexcool was clogging up the heater cores. The fix was to disconnect the heater hoses from the engine and flush the heater core out with water using a garden hose.

I did this to my 96 Impala SS in the winter of 97 and can tell you that the Orange/Brown muddy goo that came out was enough for me to flush the entire cooling system on that LT1 and refill with the good ole' green stuff.

The TSB for this fix stated that the cause was a lack of use of the heaters during the summer which led to the buildup of the Dexcool goo in the core and heater hoses.

With that in mind, I would hate to think of what Dexcool muddy goo might be doing to a LT5 that is only a sunny day driver.

JMHO-YMMV......

[TommyL]

Originally Posted by scottfab

Oh boy, this is great. An actual dealer that will corroborate the story of head gasket failure due to or “connected with” Dexcool. Can I get the name of the dealer? I won’t mention where I heard it just confirm the issue with the 4.6 V6. The dealer is in Ontario?
I just want to nail this down so that I might convert back to the green stuff. Or if the issue is still related to the nylon/Silicone type gaskets then I will report on that.

Brian Finch Pontiac Buick GMC Ltd. 1-888-257-4354

Give them a call!

[TFENT]

I had this same issue with my 96 Impala SS. There were rumors of GM using some kind of clay tabs but I flushed the system and installed a 75/25 combination of Distilled water (75%) Amsoil antifreeze (25%) with 2 bottles of water wetter and a bottle of RMI-25. Zero issues to date since. I also run this combination in all my vehicles.

[scottfab]

Yup, heard about the brown messy stuff too. That is a well known issue. I think the reason posted was contamination (bacteria?) but again, I have never seen it in mine.
Maybe cause I flushed it well enough on conversion or maybe because I used distilled water or maybe because I am lucky? Who knows.
Central issue (for me) is the gasket errosion being blamed on Dexcool.
If I can nail that one down it would be great.

[LT5-Lee]

I have been reading along and figured I might offer one piece of info to really complicate things further?

I also have been using DEX-COOL in my Z for 8 years or so, but it has only seen around 13,000 miles and I also installed one of those Rad Caps, with the hanging zinc anode, which is gone now so I figure it worked, but I have not been able to find another RAD CAP replacement as they seem discontinued? I did notice some brown gunk in the overflow tank.

I figured I would just fab another anode on the chain, but now I also want to flush the system so I hope you guys figure out the BEST possible. I know I would squeeze the "jolly juice" out of a gofer if it would keep me from a HG problem!

[TFENT]

I highly recommend using the RMI-25 to initially flush the system then add another bottle after the flush to keep the system clean. My Overflow bottles are spotless after years and years of either storage or running.

[LT5-Lee]

Originally Posted by TFENT

I highly recommend using the RMI-25 to initially flush the system then add another bottle after the flush to keep the system clean. My Overflow bottles are spotless after years and years of either storage or running.

RMI-25..? HUmmm, I never heard of it. You might have made one gofer very happy!

[TFENT]

Originally Posted by LT5-Lee

RMI-25..? HUmmm, I never heard of it. You might have made one gofer very happy!

Here is a link where i get it from. There is a short video showing it working. http://www.technilube.com/rmi25/index.php