Coolant Maintenance Guidelines

January 23, 2018

Regarding routine coolant maintenance, Luke Miller, Blackstone Labs, recommends periodic sampling by a qualified laboratory to provide an overall indication of the coolant’s physical condition and the presence of contamination, including hydrocarbon testing to detect fuel or oil in the coolant—perhaps indicating a failed fuel-injector cup or leaking oil cooler.

Frequency of laboratory testing, says Emily Featherston, data analyst, level 3, Polaris Laboratories, is recommended semi-annually for long-haul trucks and quarterly for heavy-duty applications that entail high hours, such as construction, mining, and oil-and-gas operations.

Miller and Featherston offer a few basic guidelines for coolant maintenance:

  • Follow the OEM’s recommendation for antifreeze type and maintenance, noting that some ELC coolants might require an additive “extender” at mid-life.
  • Know the fluid type being used before performing cooling-system maintenance.
  • At every PM interval, check coolant appearance, pH, freeze point, and, if possible, the inhibitor level with a test strip.
  • Don’t cross-contaminate coolants when topping off—use a 50/50 mix of the proper antifreeze and distilled/deionized water; inproper top-off mixtures can change the freeze point.
  • If cross-contamination of antifreeze types occurs by improper topping off or other maintenance procedures, ask the antifreeze supplier about remedies; some have “correction fluids” designed to restore original additive concentrations when antifreeze types are mixed or dilution with water occurs; in some instances, depending on the extent of cross-contamination, the best remedy might be to drain, flush, and refill—an expense that might pale in comparison with the potential expense of repairing or replacing a damaged engine.