Dave,
The latest issue of Automotive Rebuilder ( a "trade" only magazine) had an interesting article about coolants. One of the many points it brought up is that the extended life coolants such as Dexcool do not realy do a great job protecting the older copper and brass type radiators and heater cores. Apparently the biggeest problem is with the solder. The article recommended that if you are using Extended Life Coolants in an older system, that it be checked very often and replaced at the slightest indication of any corosion. Now I am not claiming to be an expert on this subject, but I do know that the good old "green stuff" has been protecting my cars since I started driving in 1966 and I have never had a single cooling system problem. I will also tell you I am not always the best at routine maintenance as far as coolant goes...the Prestone in my 73 Z-28 has been in there at least 4 years and still tests good and looks like new. My new Tahoe has the Dexcool in it, but I am seriously thinking of changing back to the "old" stuff the first time I change it, you can at least bet I will keep a very good eye on it.
Just my opinion, I think the jury is still out on the stuff.
P.S. The article also recommended using nothing but distilled water, this was another subject covered in a past post that I still don't have a good reliable answer to.
Merry Xmas,
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Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Heavy Chevy - original owner
Team Chevelle #100
[This message has been edited by BillK (edited 12-24-1999).]