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1,598 Posts
Discussion Starter · #1 ·
What coolant is needed or used in Cummins? im not sure if its anything special or not. i checked the bottle and its about at the add mark so id like to keep it up.

654 Posts
regular green coolant is what cummins recommends. They prefer you not to use any extended life or anything like that.

Former Staff Member
2,291 Posts
From the 2001 factory service manual

The presence of aluminum components in the cooling
system requires strict corrosion protection. Maintain
coolant at specified level with a mixture of
ethylene glycol based antifreeze and water. If coolant
becomes contaminated or looses color, drain and flush
cooling system and fill with correctly mixed solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.

CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethylene-
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle operating
conditions. The recommended mixture of 50/50
ethylene-glycol and water will provide protection
against freezing to -37 deg. C (-35 deg. F). The antifreeze
concentration must always be a minimum of
44 percent, year-round in all climates. If percentage
is lower than 44 percent, engine parts may be
eroded by cavitation, and cooling system components
may be severely damaged by corrosion.
Maximum protection against freezing is provided
with a 68 percent antifreeze concentration, which
prevents freezing down to -67.7 deg. C (-90 deg. F). A
higher percentage will freeze at a warmer temperature.
Also, a higher percentage of antifreeze can
cause the engine to overheat because the specific
heat of antifreeze is lower than that of water.
Use of 100 percent ethylene-glycol will cause formation
of additive deposits in the system, as the corrosion
inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149 deg. C (300) deg. F). This temperature is hot
enough to melt plastic and soften solder. The
increased temperature can result in engine detonation.
In addition, 100 percent ethylene-glycol freezes
at 22 deg. C (-8 deg. F ).
It’s overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32 deg. C (-26 deg. F).
5 deg. C higher than ethylene-glycol’s freeze point.
The boiling point (protection against summer boilover)
of propylene-glycol is 125 deg. C (257 deg. F )
at 96.5 kPa (14 psi), compared to 128 deg. C (263
deg. F) for ethylene-glycol. Use of propylene-glycol
can result in boil-over or freeze-up on a cooling system
designed for ethylene-glycol. Propylene glycol
also has poorer heat transfer characteristics than
ethylene glycol. This can increase cylinder head temperatures
under certain conditions.
Propylene-glycol/ethylene-glycol Mixtures can cause
the destabilization of various corrosion inhibitors,
causing damage to the various cooling system components.
Also, once ethylene-glycol and propylene-glycol
based coolants are mixed in the vehicle, conventional
methods of determining freeze point will not be accurate.
Both the refractive index and specific gravity differ
between ethylene glycol and propylene glycol.
Coolant flows through the engine block absorbing the
heat from the engine, then flows to the radiator where
the cooling fins in the radiator transfers the heat from
the coolant to the atmosphere. During cold weather the
ethylene-glycol coolant prevents water present in the
cooling system from freezing within temperatures indicated
by mixture ratio of coolant to water.

ethylene-glycol is all I have seen in the stores.

26,035 Posts
Standard old green anti-freeze coolant (Prestone)... And tapwater...

But the secret is making sure you change your coolant every 30K miles as suggested by Dodge/Cummins.

After 100K miles I've got no rust, lime/scale build up, overheating problems etc...Here is my truck after 5 years and 100K miles...:w:

So all these fancy coolants and distilled water and blah blah blah is all for the birds... Just change you coolant and flush the system every 30K miles and never worry again... Apparently I've done something right to have a cooling system that is spotless 5 years later...


1,130 Posts
how many gallons do our trucks take? I need to do a flush ASAP as my coolant looks like poo.

26,035 Posts
how many gallons do our trucks take? I need to do a flush ASAP as my coolant looks like poo.
22.7 L (24.0 qts.) according to the book...
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