GB/T 6538-2010 Determination of apparent viscosity of engine oils — Cold cranking simulator method (historical study)

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

GB/T 6538-2010 specifies the determination of the apparent viscosity of engine oils with the cold cranking simulator (CCS), and this page summarizes its version identity, scope, principle, apparatus, calibration oils, manual and automatic routes, reporting and precision.

Evidence note: original historical learning material based on the 2010 original of the same edition; it was abolished on 12 October 2022 and fully replaced by the 2022 edition. The numbers listed serve for limited comparison with the original figures, and complete technical review is pending. This is not the full standard text or a controlled operating procedure; precision is not batch certificate uncertainty.

Version identity and historical use: Original PDF physical pages 1, 2. This material is compiled from the original of the same edition of GB/T 6538—2010, published on 2 September 2010 and implemented on 1 December 2010, replacing the 2000 edition. The official 2010 record shows abolition on 12 October 2022, and the 2022 record lists full replacement of the 2010 edition. This page is for historical method study only and is not a basis for current work. The two official services belong to the same standard information system; metadata is not independent technical acceptance.

Scope and interpretation boundaries: Original PDF physical page 4. Chapter 1 gives engine oils from −5 to −35 °C and 500 to 25 000 mPa·s, with a shear stress of about 50 000 to 100 000 Pa; the measuring capability depends on the instrument model and software. The original prints the shear rate sequence as 10⁵ s⁻¹ to 10⁴ s⁻¹; the sequence and its connection are retained for technical verification and are not swapped on one's own initiative. The method lists both manual and automatic routes, and Annex A gives a dedicated manual procedure for highly viscoelastic samples; the method conditions must not be taken as product storage conditions.

Principle and the use of CCS: Original PDF physical pages 3, 5. A motor drives the rotor, the sample fills the gap between rotor and stator, and after the stator temperature is controlled the apparent viscosity is obtained from the calibrated speed relationship. The introduction links CCS with low-temperature starting, but states explicitly that it is not suitable for predicting the low-temperature flow properties of oil pumps and distribution systems, nor can it accurately predict the starting performance of a given oil sample in a specified engine.

Apparatus and temperature control: Original PDF physical page 5. The manual apparatus contains a motor, tachometer, current adjustment and stator temperature control, with the set temperature controlled within 0.05 °C; the automatic apparatus adds a computer interface and a sample introduction system. General coolant refrigeration requires a supply temperature at least 10 °C below the test temperature; thermoelectric refrigeration with circulating water or a suitable liquid is set at about 5 °C; the two conditions are not merged into one. Complete installation, guarding and control verification still require controlled documentation.

Reagents and calibration oils: Original PDF physical page 6. Chapter 6 separately lists analytical grade acetone, anhydrous ethanol, anhydrous methanol and 60–90 °C petroleum ether; flammability and health protection cannot be omitted. Table 1 lists 13 calibration oils and their approximate viscosities; the accurate viscosity must be obtained from the documentation of the specific calibration oil; the brand names, software footnotes and approximate values in the table do not prove the values or availability of any product batch. The complete 13-row cross-temperature matrix is not reconstructed, and the oil selection grouping of the 2022 edition is not applied to this edition.

Sampling and sample handling: Original PDF physical page 6. Obtain a representative sample free of suspended solids and water according to GB/T 4756. If the sample temperature is below the room dew point, it should be brought back to room temperature before opening the container; original Chapter 8 permits filtration or centrifugation to remove particles larger than 5 μm. Do not vibrate the sample before the test, to avoid entrained air. These are the handling conditions of the 2010 original and cannot be replaced by the filtration provisions of other editions.

Calibration of the manual route: Original PDF physical page 7. After commissioning a new machine or replacing the viscosity cell or drive components, check the current, repeating monthly at first; after the change is less than 0.020 A for several consecutive months, change to every three months. With a calibration oil of about 3500 mPa·s at −20 °C, set the speedometer reading to 0.240 ± 0.010; the original calls it a reading and no speed unit unconfirmed by this edition is added. For the narrow range, use at least three calibration oils covering the viscosity range. Original 9.1.3 refers to Chapter 11 while the manual test chapter is 10; the cross-reference query is retained and not unified on one's own initiative.

Calibration relationships and variables: Original PDF physical pages 7, 8. Equation (2): η = b₀/N + b₁ + b₂N; equation (3): ηN = b₀ + b₁N + b₂N². η is the apparent viscosity, N the observed tachometer reading, and the coefficients are obtained from the calibration oil data and must not be back-calculated from approximate table values. Original 9.1.4.1 says not fewer than three calibration oils and 9.1.4.2 says more than three sets of data; both formulations are retained separately; this page does not provide regression, chart reading or an on-machine calculator.

Calibration of the automatic route: Original PDF physical page 8. The automatic current check is likewise monthly at first, then every three months after the change is less than 0.020 A for several consecutive months. With a calibration oil of about 3500 mPa·s at −20 °C, adjust the displayed Speed to 0.240 ± 0.005 reading; this is not to be confused with the manual ±0.010. For the narrow range, use at least four calibration oils covering the viscosity range; original 9.2.4 separately writes at least four sets of data in the regression, the wording is retained and no automatic outlier rejection rule is added. When the deviation of the check result is greater than ±5%, recheck the temperature and re-measure.

Manual test and checks: Original PDF physical pages 8, 9. Check before a series of determinations; if the current differs from the 9.1.2 setting by more than 0.005 A, reset it and observe the adjustment after running for 15 s; if the viscosity difference is greater than ±5%, first re-run to confirm, then calibrate according to the original. A full check with reference samples every 6 months is recommended. Samples with a kinematic viscosity at room temperature above 100 mm²/s may be heated but not above 50 °C. Cool to −20 °C in 30–60 s and to −30 °C in 60–90 s; start the motor 180 ± 3 s after the coolant starts to flow, and record the reading 60 ± 5 s after starting. Different timing origins must not be merged.

Cleaning and automatic operation: Original PDF physical page 9. The manual route may follow 10.3, cleaning and drying with hot ethanol or methanol at 35–45 °C together with petroleum ether and acetone, or replacing solvent cleaning with a rinse of more than 30 mL of the next sample. Automatic 11.2 fills a 60 mL glass bottle with the sample, and the computer controls rinsing, temperature, motor and calculation. Before formal work, check with a calibration sample or secondary standard oil; a result deviating by more than ±5% from expectation is suspect; the sample volume, averaging period or two-consecutive-set criterion of the 2022 edition must not be applied.

Reporting of results: Original PDF physical pages 9, 10. Manual 12.1 obtains the apparent viscosity from the calibration curve or equation (2), with the result accurate to 10 mPa·s and the temperature recorded; automatic 12.2 reads the calculated value and temperature from the display, likewise accurate to 10 mPa·s. Both reporting rules of this edition are retained, and the automatic reporting rule of the 2022 edition is not substituted.

Precision and bias boundaries: Original PDF physical page 10. Chapter 13 is at the 95% confidence level. The manual statistics use CCS-2B, samples at −5 to −30 °C and 1560 to 10 200 mPa·s; the automatic statistics cover 9 laboratories, 10 engine oils, CCS-4/5 and software 4.X or higher, at −10 to −35 °C and 2800 to 18 000 mPa·s. Each r/R is a percentage of the mean of the two results and must not be extended to the whole method range, to other instrument routes or to batch certificate uncertainty. 13.3 states that there is no bias by method definition, which does not prove that the instrument has no error or that a product batch is unbiased. Route | Repeatability r (percentage of the mean of the two results) | Reproducibility R (percentage of the mean of the two results) Manual, Clause 13.1 | 5.4% | 8.9% Automatic, Clause 13.2 | 2.6% | 7.3%

High viscoelastic procedure and unverified items: Original PDF physical pages 4, 7, 11, 12. Normative Annex A gives a separate manual high-viscoelastic procedure: the liquid level is about 1 mm above the rotor, timing starts on reaching the test temperature, make-up sample at 10 ± 2 s, motor start at 30 ± 2 s, and reading to 0.001 unit at 10 ± 2 s after motor start. The precision of A.9 is not determined, and the body r/R is not applied. The original shear rate sequence, the normative reference parenthetical ISO 3710:1988 and the manual calibration cross-reference are retained for technical verification; the whole Table 1 matrix and software footnotes, the Figure 1 curves, and the assembly/cleaning/guarding/software controlled procedures are not reconstructed. The references are CRC 409, ASTM D2602 and STP 621, and historical citations do not imply present-day equivalence or product applicability. Annex A action | Timing origin | Original time Add make-up sample | Timer started on reaching test temperature | 10 ± 2 s Start motor | Same timer start | 30 ± 2 s Record tachometer reading | Motor start | 10 ± 2 s

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