Zerex Heavy Duty Extended Life Antifreeze/Coolant, Ready to Use - 1gal (ZXEDRU1) A 50 percent to 70 percent concentration range is suggested for optimum performance Long life and characteristics may be diminished by mixing with light duty or non-fully formulated coolants Meets the performance requirements of ASTM D6210 and Caterpillar EC-1 long-life spec Terex Approved. Thermo King, Link Belt, Cummins 3666286, Cummins 14603 and other manufacturer specifications