4.1 This test method, by a closer approach to engine cooling system conditions, provides better evaluation and selective screening of engine coolants than is possible from glassware testing (Test Method D1384). The improvement is achieved by controlled circulation of the coolant, by the use of automotive cooling system components, and by a greater ratio of metal surface area to coolant volume.

4.2 Although this test method provides improved discrimination, it cannot conclusively predict satisfactory corrosion inhibition and service life. If greater assurance of satisfactory performance is desired, it should be obtained from full-scale engine tests (Test Method D2758) and from field testing in actual service (Practice D2847).

4.3 Significance and interpretation of the test and its limitations are discussed further in Appendix X1.

4.4 If this test method is used as a qualification test for Specification D3306 and Specification D4985, the recommended components listed in Section 5 shall be used. If it is not being used for such qualification purposes, then suitable substitution components may be used, if agreed upon between the contracting parties.