300 degree COOLANT

[Shannen Durphey]

David A. Cooley wrote:
> 
> At 10:02 PM 10/12/98 -0400, you wrote:
> >Correct me if i'm wrong, but doesn't GM say not to use propylene glycol
> >antifreeze in their engines?
> >
> 
> Nope... In fdact, I believe it was late 1995 early 1996, GM started using
> "Dex-Cool" in all their vehicles (100,000 mile extended life coolant).  It
> is Propylene Glycol based.  If you mix the Propylene Glycol based coolant
> with the Ethylene Glycol coolant it will gel and basically plug the coolant
> passages of the engine.  Best to start with the PG based or flush the heck
> out of it... Also, GM recomends using distilled water with the PG coolant
> as the minerals in tap water can reduce the life of it as well.
> Later,
> Dave
> 
Just checked out some info.  GM has changed it's position on Propylene
Glycol (Bulletin # 43-62-01B).  Propylene glycol meeting GM spec is OK
and does not void warranty, but should not be mixed with ethylene
glycol, because it's difficult to measure the concentration.  PG can be
mixed with EG without harm, but the percentage of PG must be kept low so
freeze protection can be accurately measured.

Dex-cool is ethylene glycol, silicate free style.  Dex-cool can be mixed
with "green" antifreeze without any change to the freeze protection,
unlike propylene glycol (which cannot be accurately tested if mixed with
EG). However, mixing conventional antifreeze and dex-cool will eliminate
the extended change interval.  GM bulletin # 53-62-01 explains this.

Using distilled water is well worth the effort, especially in areas
where tap water has high mineral content,  Spring water is about the
worst I've seen.

Shannen

  
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>            David Cooley N5XMT           Internet: N5XMT at bellsouth.net
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