[Sci-Fi]

Actually the service manual does mention using distilled water (see below):

From the Service Manual:

COOLANT

DESCRIPTION

CAUTION: Use of Propylene Glycol based coolants
is not recommended, as they provide less freeze
protection and less corrosion protection. Do not
mix coolant types. If coolant other than Mopar®
Antifreeze/Coolant, 5 Year/100,000 Mile Formula or
equivalent is added, the mixed coolant will have a
reduced service schedule.

The use of aluminum cylinder heads, and water
pumps requires special corrosion protection. Mopar®
Antifreeze/Coolant, 5 Year/100,000 Mile Formula or
equivalent ethylene glycol based coolant with corrosion
inhibitors (called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% Ethylene Glycol and 50% distilled
water to obtain a freeze point of -37°C (-35°F). If it
loses color or becomes contaminated, drain, flush,
and replace with fresh properly mixed coolant solution.
Mixing of coolants other than specified (non-
HOAT), will reduce the 5 year/100,000 mile corrosion
protection.