1.1 本试验方法涵盖了如何在低温下测量用过的和含烟尘的发动机机油的表观粘度。 1.2 剪切速率约为0.2  s -1 在低于200 Pa的剪切应力下产生。当样品以3%的速率冷却时，连续测量表观粘度 °C/小时−5. °C至−40 °C。 1.3 本试验方法得出的测量值为粘度、最大粘度增加速率（凝胶指数）和凝胶指数出现的温度。 1.4 在制备本试验方法时，尚未确定对发动机机油以外的石油产品的适用性。 1.5 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 低温、低剪切速率、机油流变学的意义- 发动机机油（无论是新的、用过的还是用过的）的低温、低剪切粘度特性决定了机油是否会流向油底壳进口滤网，然后流向油泵，然后流向发动机中需要足够润滑的部位，以防止发动机在冷温启动后立即或最终损坏。 已经确定了两种形式的流动问题， 3. 流动受限和空气约束行为。第一种形式的流动限制，即流动限制行为，与油的粘度有关；第二，空气结合行为，与凝胶有关。 5.2 试验方法的重要性- 本试验方法采用的温度扫描技术旨在通过提供机油在使用温度范围内流变状况的连续信息，确定发动机机油对流量限制和空气结合反应的敏感性。 3. , 4. , 5. 通过这种方式，在一次试验中获得了粘度和凝胶反应。 注1: 该测试方法是与泵送性相关的三个问题之一。通过其他两种可泵性测试方法测量低温粘度， D3829 和 D4684 ，将样品保持在静态，并在高达15 s的剪切速率下产生样品的表观粘度 -1 剪切应力高达525 Pa在先前选择的温度下。测试参数（剪切速率、剪切应力、样品运动、温度扫描等）的这种差异可能导致这些方法与某些测试油之间测得的表观粘度的差异，尤其是当存在与凝胶化相关的其他流变因素时。此外，这三种方法在冷却速率上有很大差异。 5.3 凝胶指数和凝胶指数温度- 进一步发展了该测试方法，以获得称为凝胶指数和凝胶指数温度的参数。第一个参数是测量当油缓慢冷却时，由油的流变响应引起的最大扭矩增加率。 第二个参数是凝胶指数发生的温度。

1.1 This test method covers how to measure the apparent viscosity of used and soot-containing engine oils at low temperatures. 1.2 A shear rate of approximately 0.2  s -1 is produced at shear stresses below 200 Pa. Apparent viscosity is measured continuously as the sample is cooled at a rate of 3 °C per hour over the range of −5 °C to −40 °C. 1.3 The measurements resulting from this test method are viscosity, the maximum rate of viscosity increase (Gelation Index) and the temperature at which the Gelation Index occurs. 1.4 Applicability to petroleum products other than engine oils has not been determined in preparing this test method. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Significance of Low Temperature, Low Shear Rate, Engine Oil Rheology— The low-temperature, low-shear viscometric behavior of an engine oil, whether new, used, or sooted, determines whether the oil will flow to the sump inlet screen, then to the oil pump, then to the sites in the engine requiring lubrication in sufficient quantity to prevent engine damage immediately or ultimately after cold temperature starting. Two forms of flow problems have been identified, 3 flow-limited and air-binding behavior. The first form of flow restriction, flow-limited behavior, is associated with the oil's viscosity; the second, air-binding behavior, is associated with gelation. 5.2 Significance of the Test Method— The temperature-scanning technique employed by this test method was designed to determine the susceptibility of the engine oil to flow-limited and air-binding response to slow cooling conditions by providing continuous information on the rheological condition of the oil over the temperature range of use. 3 , 4 , 5 In this way, both viscometric and gelation response are obtained in one test. Note 1: This test method is one of three related to pumpability related problems. Measurement of low-temperature viscosity by the two other pumpability test methods, D3829 and D4684 , hold the sample in a quiescent state and generate the apparent viscosity of the sample at shear rates ranging up to 15 s -1 and shear stresses up to 525 Pa at a previously selected temperature. Such difference in test parameters (shear rate, shear stress, sample motion, temperature scanning, and so forth) can lead to differences in the measured apparent viscosity among these methods with some test oils, particularly when other rheological factors associated with gelation are present. In addition, the three methods differ considerably in cooling rates. 5.3 Gelation Index and Gelation Index Temperature— This test method has been further developed to yield parameters called the Gelation Index and Gelation Index Temperature. The first parameter is a measure of the maximum rate of torque increase caused by the rheological response of the oil as the oil is cooled slowly. The second parameter is the temperature at which the Gelation Index occurs.