News

Coolants

March 1, 2003

There are a large number of antifreeze products for fleets to choose from, but understanding the differences between them is sometimes a bit confusing. There are basically three types of coolants: conventional, fully formulated and extended-life. Conventional coolants, while still widely available, have become less popular among fleets because using them in heavy-duty engines means adding an initial

DEBORAH MCGUFFIE

Conventional coolants, while still widely available, have become less popular among fleets because using them in heavy-duty engines means adding an initial dose of inhibitors. The system must be tested and inhibitors added again at regular intervals to avoid creating a cooling system failure.

Fully formulated coolants, also known as pre-charged coolants, come ready to use, as they already contain an initial dose of supplemental coolant additives (SCA). Finally, there are the newer extended life coolants, which are fast becoming the standard product among fleets because of their reduced maintenance requirements.

Almost all major antifreeze suppliers have extended life coolants (ELC) in their product lineups. Fleetguard, for example, offers ESXtreme, an organic acid formulation that is borate-, phosphate- and silicate-free. Valvoline offers the Zerex Extreme extended life coolant.

ChevronTexaco Global Lubricants, which manufactures Delo Extended Life Coolant, says fleets specifying a coolant for their heavy-duty diesel trucks should consider a product that will provide them with the best cooling system protection they can have.

Since extending vehicle life is a key concern for today's fleet manager, ChevronTexaco notes that ELC products, which offer longer component durability, are gaining interest among fleets.

With extended life coolants, Shell adds, fleets can in many cases run their heavy-duty diesels to overhaul with no SCAs or coolant changes necessary, and at no sacrifice to engine or cooling system reliability. Shell's “fill for life” Rotella ELC organic additive technology (OAT) coolant is said to be good for a minimum of 600,000 miles, with the addition of just one Rotella extender at 300,000 miles.

Shell notes that coolants are not something a fleet should worry about only when the weather gets cold, but are a year-round maintenance item, just like oil. Yet, too often coolant is neglected. This is especially a problem in trucks that are away from their home terminal for long periods of time.

Cooling system failures, in fact, are the biggest cause of engine failure, according to Shell. The company says extended life coolants provide fleets with added security since the SCAs in them do not deplete over time.

Fully formulated coolants are also popular choices with fleets because they are more economical than ELC. They come pre-charged with SCAs to protect heavy-duty diesel engines for up to 20,000 miles of operation.

Kost USA (www.kostusa.com), which supplies antifreeze in bulk to customers like D-A Lubricants and Castrol Heavy Duty Lubricants, says that with the 2002 EGR diesels it's become imperative for fleets to use coolants with SCAs in them. SCAs, typically a nitrite or molybdate compound, are especially designed to protect cylinders from erosion, prevent scale and increase specific heat capability of the ethylene glycol base fluid.

Kost pre-charges its antifreeze with SCAs. It says fleets should test the system twice a year and top-treat with SCAs as needed. Kost antifreezes come pre-diluted with deionized water so they are easy to use for flush and fill, as well as for topping off coolant when needed.

Kost says fleets should only use deionized or distilled water since tap water contains minerals that can contaminate the cooling system. Scaling — the term used when these deposits collect on metal engine surfaces — restricts the flow of heat to the coolant.

Fleets might also consider looking at products low in phosphates. While phosphates are effective as an inhibitor in antifreeze chemistry, they also may contribute to engine scaling.

Finally, it should be noted that although most coolants on today's market use ethylene glycol (EG) for the base fluid, propylene glycol (PG) products are also available, such as the Sta-Clean heavy-duty, long life antifreeze. Although more expensive, PG is totally non-toxic.