As far as I see it, the biggest enemy of the radiators in Japanese makes
are silicate corrosion inhibitors.  Silicates inevitably come out of
suspension, and may clog up the small passages in these radiators.  Most
Japanese makers use a silicate/borate-free coolant with phosphates as
corrosion inhibitors.

These seem to be the types of OEM coolants out there:

**Japanese standard: No silicates or borates.  High levels of phosphate
corrosion inhibitors.

**Japanese extended life: similar to Dex-Cool or other OAT coolants.
May contain phosphates.

**Extended-life organic acid technology (OAT) coolants:  Dex-Cool is the
prime example.  No silicates, borates, nitrates, nitrites, or phosphates.
Some have called into question how effective they are given that they
rely on organic acid corrosion inhibitors alone.

**Hybrid OAT coolants: Chysler and Zerex G-05.  Similar to OAT coolant,
but with low-silicate levels as a corrosion inhibitor.  Seems to be
used by Ford, Daimler-Chrysler, and other European carmakers.  No
phospates.  Phosphate-free seems to be important in Europe, where high
mineral content water is the norm.  Phosphates apparently cause the
minerals to precipitate out and becomes abrasive.

Aftermarket coolants:

**Traditional silicated: Yellow prestone, Peak, Zerex, etc.  This seems
to be the type generally used in American cars with changes up to
30K miles or 2 years.  I can't think of any volume carmaker who would
still use this kind of coolant as OEM.  The newer versions allegedly
contain less silicates than in years past.

**Low-tox propylene glycol: Prestone low-tox, Sierra, etc.  Propylene
glycol is essentially non-toxic in small amounts and is used in food
and medicines.  It has lower boilover temp and a higher freezing temp.

There is no OEM coolant??? Are Canadian cars delivered to the dealer from
SOA without any coolant??? I go with Rick and stick with Vehicle OEM fluid
as a safety precaution ands to avoid any warranty issues down the road. Ed