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How many coolants should you keep on hand?
by Ed Eaton
From Jan/Feb 2001 Cool Profit$ Magazine
© 2001 All rights Reserved
The days of simply grabbing a jug of green stuff to top off a customer’s radiator are gone. But how many do you really need to keep on the shelf?

Minimum: at least two. If you want to keep the inventory to a minimum and still be able to handle anything that comes in the door, here is what you need to stock:

1. DEX-COOL® to service 1995 and newer GM cars and trucks.

2. A fully-formulated coolant, such as Ford or Daimler-Chrysler’s new G-05® hybrid, Prestone® Heavy Duty, FleetCharge®, or Fleetguard Compleat® can be used in all other engines. This product will cover both your traditional green and other Long Life needs. Make sure it says that it meets ASTM D6210 specifications on the label!

The first one is obviously for late model GM cars and light duty trucks. The second covers the rest of the field, including cars and diesel powered vehicles. Note that the latter will cost about a buck a gallon more than the traditional green product.

Background and reasons for our recommendation. Until 1995 most automotive coolants sold in North America were compatible with one another. Heavy truck owners were beginning to use some more sophisticated technologies, but a lot of those customers were using the same coolant that they had for 20 years! In general, buying quality antifreeze and mixing it 50-50 with water was the only requirement. Big truck operators needed supplemental coolant additives (SCAs) to protect diesel engines.

Oh how the situation has changed! GM cars now use DEX-COOL. Though still an ethylene glycol based coolant, the anti corrosion chemistries are dramatically different.

As a laboratory compatibility test, we intentionally mixed DEX-COOL with a conventional coolant and subjected the mixture to a sample of fresh aluminum. The resulting data suggests that aluminum corrodes at an accelerated rate when subjected to this mix compared to pure DEX-COOL or pure conventional coolant. As a result, Amalgatech recommends that the coolants not be mixed.

Further, it is our experience that it is best to maintain GM vehicles with genuine DEX-COOL through the warranty period of 5 years, 150,000 miles. After the extended cooling system warranty has expired, the end user is on his own anyway, so any quality extended service coolant is a good choice. PEAK® and Prestone® both have products that are available. It’s best to stay with extended life coolants in the 1995 and newer GM cars.

Note 1. DEX-COOL was initially dyed orange. In 2000 model year cars, most of the GM coolants that we’ve seen are pink in color. All of the aftermarket supply that we’ve seen so far however, remains orange.

Note 2. Ford presented a technical paper years ago that concluded that the conventional ‘green’ factory fill coolant that they used was just as durable as carboxylate-inhibited coolants, like DEX-COOL. Nevertheless, Ford and Daimler-Chrysler both appear to be changing to an advanced hybrid technology in the 2001 or 2002 model year cars. This coolant is easy to identify because it is golden yellow. It offers the same extended life benefits as DEX-COOL, but without the compatibility questions. Further, it meets the new ASTM D6210 specification so it can be used in diesel trucks.

Note 3. The diesel engine community has now embraced fully-formulated coolant as defined by ASTM D6210. These coolants do not require any initial additives, but for diesels they must be supplemented. Most can be operated for the life of the engine, using advanced maintenance strategies such as the Penray Need-Release® or Fleetguard ‘ES’® filter systems.                           $$$

Editor: Ed Eaton is Chief Engineer of Amalgamated Laboratories.
E-mail at: ereaton@amalgatech.com.
2965 West Osborn Road, Phoenix, AZ 85017-4927
Phone: 602-252-0280; Fax: 602-252-0282

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