Important of Coolant Changes vs Topping Off

I had my radiator flushed and filled on my 1989 Chevy S10 Blazer 3 years
ago. Since then I've simply topped it off each year. How important is it to
completely flush the system every 2-3 years? Does it really make a
difference in the life of the radiator and/or engine?

On Sat, 9 Oct 2004 21:56:33 -0400, "Spiderman"
> wrote:

>I had my radiator flushed and filled on my 1989 Chevy S10 Blazer 3 years
>ago. Since then I've simply topped it off each year. How important is it to
>completely flush the system every 2-3 years? Does it really make a
>difference in the life of the radiator and/or engine?
>

Yes. The coolant contains additives to help protect the cooling
system from corrosion. Just like in oil, these additives can break
down over time. Also, just like oil, the coolant mix can become
dirty, neccessitating a change. Change it again soon.

Spiderman wrote:
> I had my radiator flushed and filled on my 1989 Chevy S10 Blazer 3 years
> ago. Since then I've simply topped it off each year. How important is it to
> completely flush the system every 2-3 years? Does it really make a
> difference in the life of the radiator and/or engine?
>
>
One question - where's the old coolant going? How much are you adding?
If you're adding a lot of coolant on a regular basis, I'd fix the leak
first...

Ray

Spiderman wrote:
>>>I had my radiator flushed and filled on my 1989 Chevy S10 Blazer 3 years
>>>ago. Since then I've simply topped it off each year. How important is it
>>>to completely flush the system every 2-3 years? Does it really make a
>>>difference in the life of the radiator and/or engine?

> There's no leaking...I just add a little bit to the overflow tank about once
> a year to top it off. The engine temperature gauge is always in normal
> operating range.
>

Ok, define a little bit - a cup, a gallon?

And yes, you should change the coolant on a regular basis. A flush is
overkill, but you should at least drain most of it and refill with fresh
coolant and clean water.

http://www.angelfire.com/ia2/vmax/coolantnotes.htm

has a bunch of good quotes (and some annoying popups) explaining how
coolant gets "used up" over time. The coolant doesn't get used up, the
anti-corrosion inhibitors get used up.

And, if you own an old car that wasn't maintained properly before you
bought it, you'll usually flush all sorts of gunk out when you start
changing the coolant.

Story: Friend bought a used 77 Dodge van for $1 back in about 92.
brown stuff in the leaking rad. Swapped rad, flushed coolant. Twice.
Two days later, had to do it again. Took it to a shop a week later
because it was still brown. They powerflushed it. A week later they
did it again for free because it was still brown. It took a total of 7
flushings before the coolant would stay green for more than a week.
(it was a slant-six, so it was pretty much indestructible - I think it
might still be on the road today...)

Ray