> wrote in message
...


and I didn't realize until just here recently that the silicate in the
yellow jug of

prestone coolant was hostile to water pumps. this situation may not be
peculiar to only prestone.

m h o
v fe

Look...lets see if we can get it a little straighter.
Silicate has always been in 'green' coolant and its purpose is as a
corrosion inhibitor for aluminum parts.

Some water pumps have been made of aluminum.. Nicht wahr?

Silicate is not intended to protect iron or steel.

When excess silicate was used in a formulation, or when certain types
of hard water were used to fill the radiator, silicate precipitation could
be problematic.
(Magnesium in the water is particularly incompatible.)

Precipitates are never good in a cooling system.. They can block
radiators, AND they can be abrasive. MANY times I have seen
radiators plugged with silicate precipitate. It is DIFFICULT to
remove.

OAT technology, as used in Dexcool, did not contain silicates. That
was seen to be an advantage in one sense, but probably did not provide
the protection to aluminum parts that was desirable.

Therefore Hybrid OAT , or HOAT, evolved. HOAT contains silicate,
but in reduced amounts compared with the older green formulas.

The city water here contains little magnesium or other hardness ions.

I have used green coolant in my Dodge van for a long time and there
is no trace of a problem.

We used Dexcool in my wife's Buick because we knew the damn plenum
was likely to go, and I didn't want chicken**** GM to have an arguing
point in case the car were still in warranty. Now, that episode is over.

I would have no fear about changing to HOAT, or even to Green, now.