1.1 本试验方法包括在以受控速率冷却超过45小时后测量发动机机油的屈服应力和粘度 h至-10之间的最终试验温度 °C和-40 °C。对于-40℃的测试温度，规定了精度 °C至-15 °C。粘度测量在525的剪切应力下进行 在0.4的剪切速率上 s –1 至15 s –1 . 发现在该剪切应力下测得的粘度在粘度达到临界值的温度和发动机临界泵送失效温度之间产生最佳相关性。 1.2 本试验方法包含两个程序:程序A包括试验方法的几个设备和程序修改 D4684 –02已证明可提高测试精度，而程序B与测试方法相同 D4684 –02. 此外，程序A适用于利用热电冷却技术或近期制造的直接制冷技术进行仪表温度控制的仪表。程序B可以使用程序A中使用的相同仪器或通过循环甲醇冷却的仪器。 1.3 本试验方法的程序A的精度规定为屈服范围小于35 Pa至210 Pa和表观粘度范围为4300 mPa·s至270 000 mPa·s。该测试程序可以确定更高的屈服应力和粘度水平。 1.4 本试验方法适用于未使用的机油，有时称为新鲜机油，设计用于轻型和重型发动机应用。它也被证明适用于使用过的柴油和汽油发动机机油。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。 1.5.1 例外情况- 本试验方法使用基于国际单位制的单位毫秒（mPa·s）表示粘度，相当于厘泊（cP）。 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 当发动机机油冷却时，冷却速度和持续时间会影响其屈服应力和粘度。在本实验室试验中，新鲜发动机机油在已知蜡结晶的温度范围内缓慢冷却，然后相对快速地冷却到最终试验温度。这些实验室测试结果预测了由于缺乏抽油能力而在现场失效的已知发动机机油。 4. 这些记录在案的现场失效油均由通常在-25℃下测试的油组成 °C。这些现场故障被认为是机油形成凝胶结构的结果，该结构导致发动机机油的屈服应力或粘度过高，或两者兼而有之。 5.2 冷却曲线: 5.2.1 对于待测试的油 −20 °C或更低， 表X1.1 应用。中所述的冷却曲线 表X1.1 基于ASTM可泵性参考油（PRO）的粘度特性。该系列机油包括具有正常低温流动特性的机油和与低温可泵性问题相关的机油 ( 1- 5. ) . 5. 对于 −35 °C和−40 °C温度曲线基于ASTM进行的“现代发动机冷启动和可泵性研究”收集的数据 ( 6. , 7. ) . 5.2.2 对于待测试的油 −15 °C或 −10 °C， 表X1.2 应用。由于缺乏适当的参考油，因此尚未确定该温度分布的显著性。同样，使用该轮廓的试验方法的精度 −10 °C测试温度未知。温度分布 表X1.2 是从中的 表X1.1 温度相对于 表X1.1 ，考虑到在以下条件下测试的粘性油的预期较高浊点: −15 °C和 −10 °C。

1.1 This test method covers the measurement of the yield stress and viscosity of engine oils after cooling at controlled rates over a period exceeding 45 h to a final test temperature between –10 °C and –40 °C. The precision is stated for test temperatures from –40 °C to –15 °C. The viscosity measurements are made at a shear stress of 525 Pa over a shear rate of 0.4 s –1 to 15 s –1 . The viscosity as measured at this shear stress was found to produce the best correlation between the temperature at which the viscosity reached a critical value and borderline pumping failure temperature in engines. 1.2 This test method contain two procedures: Procedure A incorporates several equipment and procedural modifications from Test Method D4684 –02 that have shown to improve the precision of the test, while Procedure B is unchanged from Test Method D4684 –02. Additionally, Procedure A applies to those instruments that utilize thermoelectric cooling technology or direct refrigeration technology of recent manufacture for instrument temperature control. Procedure B can use the same instruments used in Procedure A or those cooled by circulating methanol. 1.3 Procedure A of this test method has precision stated for a yield range from less than 35 Pa to 210 Pa and apparent viscosity range from 4300 mPa·s to 270 000 mPa·s. The test procedure can determine higher yield stress and viscosity levels. 1.4 This test method is applicable for unused oils, sometimes referred to as fresh oils, designed for both light duty and heavy duty engine applications. It also has been shown to be suitable for used diesel and gasoline engine oils. The applicability to petroleum products other than engine oils has not been determined. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5.1 Exception— This test method uses the SI based unit of milliPascal second (mPa·s) for viscosity which is equivalent to, centiPoise (cP). 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 When an engine oil is cooled, the rate and duration of cooling can affect its yield stress and viscosity. In this laboratory test, a fresh engine oil is slowly cooled through a temperature range where wax crystallization is known to occur, followed by relatively rapid cooling to the final test temperature. These laboratory test results have predicted as failures the known engine oils that have failed in the field because of lack of oil pumpability. 4 These documented field failing oils all consisted of oils normally tested at –25 °C. These field failures are believed to be the result of the oil forming a gel structure that results in either excessive yield stress or viscosity of the engine oil, or both. 5.2 Cooling Profiles: 5.2.1 For oils to be tested at −20 °C or colder, Table X1.1 applies. The cooling profile described in Table X1.1 is based on the viscosity properties of the ASTM Pumpability Reference Oils (PRO). This series of oils includes oils with normal low-temperature flow properties and oils that have been associated with low-temperature pumpability problems ( 1- 5 ) . 5 Significance for the −35 °C and −40 °C temperature profiles is based on the data collected from the “Cold Starting and Pumpability Studies in Modern Engines” conducted by ASTM ( 6 , 7 ) . 5.2.2 For oils to be tested at −15 °C or −10 °C, Table X1.2 applies. No significance has been determined for this temperature profile because of the absence of appropriate reference oils. Similarly, precision of the test method using this profile for the −10 °C test temperature is unknown. The temperature profile of Table X1.2 is derived from the one in Table X1.1 and has been moved up in temperature, relative to Table X1.1 , in consideration of the expected higher cloud points of the viscous oils tested at −15 °C and −10 °C.