This article was trigger by some definitions supplied by Jim2 (Jim):
There once was a time when you could buy diesel coolant by color, but no more. Therefore, you need to know what kind of coolant you have in your diesel engine when you need to add coolant. You can mix colors but your can't mix coolant types.
There will be no endeavor to prove which types of coolant are better. We only intent to educate your to know what to be asking for when you buy coolant to add to your system.
We found this excellent article on RVcuzer.com by Mark Quasius that should be read first; HD Diesel Engine Coolants for RVs. We copied this article into our web site to insure it availability. The link to the original article is on the bottom of the web page.
SCA = supplemental coolant additive
The chemical cocktail added to the basic ethylene glycol or propylene glycol, to reduce scaling, corrosion & cavitation of the coolant system components.
DCA2 & DCA4 are the two different types of SCA based on their different chemical cocktails - nitrite/borate/silicate versus nitrite/molybdate/phosphate/silicate - which additive to use is specified by the engine manufacturer as part of their coolant specifications. Many recommend not mixing these two different chemical additives, some say its ok to mix them. each has pluses & minuses. Best overall approach is to follow the recommendations of your engine manufacturer.
DCA4 has been historically specified by Ford, International and Cummins.
DCA2 has been historically specified by CAT, Detroit Diesel and a few others.
Heavy Duty Conventional Diesel Coolant
This is how adding SCA's to coolant started. At initial fill of the coolant, the SCA additive is added and then periodically tested to maintain proper SCA %.
Heavy Duty Fully Formulated Diesel Coolant
This is how almost all SCA coolant is delivered today. The coolant comes pre-charged with SCA for initial fill, followed by periodic testing to maintain proper SCA %.
Heavy Duty Diesel Extended Life Coolant (ELC)
Uses a variety of proprietary "inhibitors" instead of SCA and therefore does not require testing or adding SCA, but requires the addition of an "Extender" after so many miles of use.
Organic Acid technology (OAT)
Carboxcylic/fatty acids are used to replace the function of the previously used SCAs. This type of coolant can last 6 years/ 600,000 miles with a additive recharge at 3 years/300,000 miles.
This is a transition coolant with SCAs included in OAT coolant at a much reduced level than in typical SCA coolants.
In case you missed it in the recommended article to read above, OAT Extended Life Coolant is good for 600,000 miles or 6 years what comes first but needs an Extender Charge at 300,000 miles or 3 years.
Emery Nash (Emery) found Understanding coolants with some informative reading.
Escapees HDT Forum threads on diesel coolant:
- 6/11/2010 Volvo Cooling System and Antifreeze
- 6/16/2010 Green is out, Red is IN
- 7/7/2010 Mixing Coolant Types
- 9/24/2010 Pencool & Pencool Filter?
- 11/2/2010 Coolant System on Volvo
- 3/3/2011 Davco 382 Filter
Agents are arranged in order of numbers of mentions in Forum threads.