1.1 本试验方法可自动测定传动系和液压油（如自动变速器油、齿轮油、液压油和其他润滑剂）的低温、低剪切速率粘度。它利用热电温度控制的样品室以及可编程旋转粘度计。本试验方法的粘度范围为300 mPa·s至900 000 在-40℃温度下测得的mPa·s 摄氏度至-10度 摄氏度。 1.2 精度数据确定为–40 °C和-26 粘度范围为6380°C mPa·s至255 840 mPa·s。 1.3 以国际单位制表示的数值应视为标准值。本标准中不包括其他计量单位，但下文注明的计量单位除外。 1.3. 1. 例外- 本试验方法使用国际单位制，毫帕斯卡秒（mPa·s）作为粘度单位。(1 cP=1 mPa·s）。 1.4 本标准并不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建立适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 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 自动变速器油、齿轮油、扭矩和拖拉机油、动力转向油和液压油的低温、低剪切速率粘度对于许多机械设备的正确操作非常重要。通常规定这些流体的低温粘度极限，以确保其适用性，并在许多规范中引用。 5.2 手动测试方法、测试方法 D2983 ，用于确定齿轮油或自动变速器油（ATF）是否符合最初使用特定型号粘度计定义的低温性能标准。 4. 原始ATF性能相关性研究中涵盖的粘度范围小于1000 mPa·s至60以上 000 mPa·s。 随着时间的推移，这些相关性的成功以及齿轮油和ATF性能测试方法的发展已应用于其他流体和润滑剂，如液压油等。 5.3 某些配制的流体类型可能会形成一种结构，可能是由于蜡的存在，当浸泡在某一低温或低于某一低温时。在粘度测量期间，粘度计的主轴旋转会使该结构劣化，这可能导致表观粘度随着阶跃时间的增加而降低。流体表观粘度的这种降低通常称为剪切变稀。表现出高初始表观粘度的样品可能会阻碍某些机械（如自动变速器）的润滑。 4. 然而，在测量高粘度产品（如齿轮油，尤其是使用溶剂精制基础油配制的产品）时，样品表现出剪切稀化行为并不罕见。建议，如果在ATF或类似的低粘度产品中观察到这种现象，则应仔细考虑流体的适用性。如果需要，测试方法 D5133 或 D6821 ，可用于研究这些流体的行为。 5.4 通过使用选项A的本试验方法确定的粘度与试验方法在统计上无法区分 D2983 – 根据ILS数据进行16次测量，以确定本试验方法的精度。ILS结果与开发本试验方法时评估的大量ATF和齿轮油的数据一致。 5. 5.5 由于试验温度下的时间较短，简略热调节（选项B）的结果可能与14 h在试验温度下浸泡（选项A）。对于制定本试验方法所用的样品，采用简化程序（选项B）获得的结果往往小于14 h浸泡（选项A）。对于含有高蜡基料的产品，这种差异似乎更大。

1.1 This test method automates the determination of low temperature, low-shear-rate viscosity of driveline and hydraulic fluids, such as automatic transmission fluids, gear oils, hydraulic fluids, and other lubricants. It utilizes a thermoelectrically temperature-controlled sample chamber along with a programmable rotational viscometer. This test method covers a viscosity range of 300 mPa·s to 900 000 mPa·s measured at temperatures from –40 °C to –10 °C. 1.2 The precision data were determined at –40 °C and –26 °C for a viscosity range of 6380 mPa·s to 255 840 mPa·s. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard except those noted below. 1.3.1 Exception— The test method uses the SI unit, milliPascal-second (mPa·s), as the unit of viscosity. (1 cP = 1 mPa·s). 1.4 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. 1.5 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 The low-temperature, low-shear-rate viscosity of automatic transmission fluids, gear oils, torque and tractor fluids, power steering fluids, and hydraulic oils are of considerable importance to the proper operation of many mechanical devices. Low-temperature viscosity limits of these fluids are often specified to ensure their suitability for use and are cited in many specifications. 5.2 The manual test method, Test Method D2983 , was developed to determine whether a gear oil or an automatic transmission fluid (ATF) would meet low-temperature performance criterion originally defined using a particular model viscometer. 4 The viscosity range covered in the original ATF performance correlation studies was from less than 1000 mPa·s to more than 60 000 mPa·s. The success of these correlations and the development of this test method with gear oil and ATF performance has over time been applied to other fluids and lubricants such as hydraulic fluids, and etc. 5.3 Some formulated fluid types may form a structure, presumably due to the presence of wax, when soaked at or below a certain low temperature. The viscometer’s spindle rotation can degrade this structure during the viscosity measurement, which may result in a decrease in the apparent viscosity as the step time increases. This decrease in a fluid’s apparent viscosity is often referred to as shear thinning. A sample that exhibits a high initial apparent viscosity may impede the lubrication of certain machinery, such as automatic transmissions. 4 However, it is not unusual to see a sample exhibit shear thinning behaviour when measuring high viscosity products such as gear oils, especially those formulated using solvent refined base stocks. It is recommended, that if this phenomenon is observed in ATF or similar low viscosity products, the suitability of the fluid for the application should be carefully considered. If desired, Test Method D5133 or D6821 , may be used to study the behavior of these fluids. 5.4 The viscosity determined by this test method using option A was found to be statistically indistinguishable from Test Method D2983 – 16 measurements based on the ILS data to establish this test method’s precision. The ILS results were consistent with the data obtained on numerous ATF and gear oils evaluated in developing this test method. 5 5.5 Due to the shorter time at test temperature, results from the abbreviated thermal conditioning (Option B) may differ from results obtained with the 14 h soak at test temperature (Option A). For the samples used in developing this test method, results obtained with the abbreviated procedure (Option B) tended to be less than 14 h soak (Option A). This difference seemed to be larger for products that contained high wax base stock.