Silicate-free, carboxylate based technology as typified by Texaco Extended Life Coolant (TELC) and Caterpillar Extended Life Coolant (ELC), both meeting Caterpillar's EC-1 Coolant Specification, offer excellent corrosion protection for commercial lead solders commonly used in the fabrication of copper/brass radiators and heater cores throughout the trucking industry. Results of laboratory testing using solders from commercial radiators manufacturers and extensive field coolant analysis compare extended life technology with the popular conventional coolant technologies.In the laboratory, the effect of coolant concentration on solder protection is explored using the glassware corrosion test, ASTM D-1384. At concentrations ranging from 33% up to 75% the carboxylate technology offers comparable to superior protection when compared to the popular heavy-duty conventional coolant containing silicates and phosphates.More importantly, however, real world field experience is gleaned from extensive coolant analysis. These analyses, representing a broad array of heavy-duty diesel engines using either conventional or extended life coolants, provide clear evidence of the superior solder protection offered by carboxylate technology. Coolant analysis from over 8000 engines is provided to relate coolant lead levels to coolant solder protection. As coolant concentration increases with conventional technology, the amount of lead found in the coolant sample also increases indicating the presence of active corrosion. By comparison, lead levels observed with extended life, carboxylate coolants remain low over the range of coolant concentrations observed. The low lead levels cannot be explained by solubility differences and indicate excellent solder protection at all glycol levels analyzed when using Extended Life coolant technology.Finally, examination of cooling system components taken from a truck with a million mile history on Extended Life technology confirms excellent solder protection over this extended period without the need for supplemental coolant additives as would be required if conventional technology were used.