Update: Got a response from Prestone today (quick response!).
Thank you for your inquiry and your interest in our products. To
answer your question, Prestone Extended Life 5/150 Antifreeze Coolant is
safe to use in your 2001 Dodge Intrepid and will offer excellent cooling
system protection. Prestone Extended Life Antifreeze Coolant is phosphate,
silicate, and borate free. This coolant uses a special chemistry and
technology that extends the life of the corrosion inhibitor package so that
it lasts up to five years or 150,000 miles (whichever comes first), and is
safe for all cars and light trucks (old or new).
Prestone Extended Life has been proven in the laboratory to be
compatible with all new extended life formulas at concentrations typically
used in all newer vehicles coming off the production line today. These
automobile manufacturers include Audi, BMW, Daewoo, Daimler Chrysler, Ford,
General Motors, Honda, Mercedes, Mitsubishi, Suzuki, Toyota, Volvo, and VW.
For the best protection, we recommend draining and flushing the
cooling system first in order to gain the full benefits of the
longer-lasting formula. When using Prestone Extended Life in your vehicles
cooling system and a conventional antifreeze coolant is added, you will lose
the extended life protection.
We recommend that you use between a 50% and 70% concentration of
antifreeze. At least 50% is necessary to give the adequate amount of
corrosion protection, as well as freeze/boilover protection. However, we do
not recommend a concentration of more than 70% antifreeze. This could cause
the restriction of the heat transfer capabilities, corrosion protection, and
We hope this has been helpful. If you need additional information
please let us know.