In my part of the country the authority on coolant is a company called Recochem who manufacturers coolant, this is what they have to say.
Both packaged and bulk heavy duty diesel engine coolants will be transitioned from green to purple by June 1, 2007. The change of color will not affect the performance of the coolant. Green and purple coolants can be mixed and will perform to specs.
Four Types Of Diesel Coolant Are Described below:
- Green coolant [Ethylene Glycol] needs to be pre-charged with DCA4 & tested regularily with proper test strips provided by Fleetguard.
- Purple & Pink [Ethylene Glycol] coolant is a conventional heavy duty fluid that is already precharged to specs. no treatment is required.
- Blue colored coolant is a Propylene Glycol that is the equivalent of the purple and pink mixture.
- Red has Organic Acid Technology and meets one or more of the OEM [original equipment manufacturer] specs. for International, Caterpillar, Detroit and Mack diesel engines.
Labeling close to the coolant fill tank is advisable so mixing doesn't occur with the acception of the green and purple diesel coolant.