SH/T 0299-1992 Determination of Oxidation Stability of Internal Combustion Engine Oils

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: SH/T 0299-92
• Chinese name: Determination of Oxidation Stability of Internal Combustion Engine Oils
• English name: not provided in the available source
• Replacement relationship: replaces SY 2681-82 (the source text writes "replaces SY 268182", requires confirmation against the source standard (source-text extraction))
• First issued: 1978 year (see additional notes)
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• This standard specifies a method for determining the oxidation stability of internal combustion engine oils.
• This standard applies to internal combustion engine oils.
• Not applicable: not provided in the available source.

3. Method principle

Under specified conditions, the sample is oxidized, and the mass change of metal sheets in the sample before and after oxidation, the change in kinematic viscosity at 50℃, the n-pentane insolubles after oxidation, and the acidity/alkalinity of the sample vapor are scored, and the total score is used to represent the oxidation stability of the sample. The lower the total score, the better the oxidation stability.

The test conditions are divided into two types:

• Non-intensified test conditions: oxidation temperature 160℃, oxygen flow rate 200±10 mL/min, oxidation time 6 h.
• Intensified test conditions: oxidation temperature 165℃, oxygen flow rate 200±10 mL/min, oxidation time 12 h, used for internal combustion engine oils with relatively good oxidation stability.

(Note: the original text "oxygen flow rate 20010mL/min" is source-text extraction noise; based on the context and clause 7.2 "200±10mL/min", it is determined to be 200±10 mL/min.)

4. Reagents and materials (purity / preparation)

4.1 Materials (listed in the source as 4.2 materials)

• 4.2.1 Metal sheets:
  • Iron sheet (DT1 grade iron): 76 mm × 12 mm × 0.5 mm;
  • Copper sheet (T1 grade copper: contains copper 99.95%): 76 mm × 16 mm × 0.5 mm;
  • Lead sheet (Pb1 grade or Pb2 grade: contains lead 99.99%): 76 mm × 12 mm × 0.5 mm.
  • A small hole with a diameter of 3 mm is drilled in the center at a position 5 mm above the metal sheet. Numbers are engraved on the copper and lead sheets. During testing, the copper and iron sheets may be reused repeatedly, but the lead sheet must be a new sheet.
• 4.2.2 Bamboo tongs.
• 4.2.3 Chamois leather.
• 4.2.4 Solvent naphtha.
• 4.2.5 Oxygen.
• 4.2.6 Sandpaper: 500 grade (particle size 320) and 700 grade (particle size 500).
• 4.2.7 Qualitative filter paper.
• 4.2.8 Blue litmus paper.
• 4.2.9 Distilled water.

4.2 Reagents (listed in the source as Chapter 5)

• 5.1 n-Pentane: chemically pure.
• 5.2 Petroleum ether: analytically pure, 60~90℃.
• 5.3 Anhydrous ethanol: analytically pure.
• 5.4 Benzene: analytically pure.
• 5.5 Anhydrous ethanol-benzene mixed liquid: prepared from anhydrous ethanol and benzene in a volume ratio of 1:4.
• 5.6 Sulfuric acid: chemically pure.
• 5.7 Hydrochloric acid: analytically pure, prepared into 13% (m/m) hydrochloric acid solution. (The number is missing in the source text, requires confirmation against the source standard (source-text extraction))
• 5.8 Potassium dichromate: chemically pure, prepared into chromic acid cleaning solution.

5. Instruments and equipment

• 4.1.1 Constant-temperature bath: a dedicated internal combustion engine oil oxidation stability tester capable of controlling 160±1℃ and 165±1℃, or another constant-temperature bath that can meet this requirement.
• 4.1.2 Oxidation tube: a hard round-bottom glass test tube with a length of 200±2 mm, an outer diameter of 26±1 mm, and a wall thickness of 1.5~2 mm, with a graduation line at a capacity of 40 mL.
• 4.1.3 Oxygen inlet tube: a glass tube with a length of 210±2 mm and an outer diameter of 6±0.5 mm, with an inner diameter at the outlet at the tail end of 1.8~2.0 mm, and a protruding part at a position 80 mm from the outlet for fixing the metal sheet hanging sleeve.
• 4.1.4 Metal sheet hanging sleeve: a glass ring sleeve that fits over the protruding part of the oxygen inlet tube; three claws are arranged at equal intervals around the circumference of the hanging sleeve for hanging metal sheets.
• 4.1.5 Oxygen flow meter: 0~400 mL/min.
• 4.1.6 Thermometer: 0~200℃, with a scale division of 1℃.
• 4.1.7 Contact-point thermometer: 50~200℃.
• 4.1.8 Gas washing bottle: there is a graduation line at a position 50 mm above the outlet of the gas inlet tube.
• 4.1.9 Centrifuge: rotation speed 1500 r/min, capable of holding 50 mL centrifuge tubes.
• 4.1.10 72 type spectrophotometer.
• 4.1.11 Desiccator.
• 4.1.12 Centrifuge tube: 50 mL and graduated.
• Note: If a dedicated internal combustion engine oil oxidation stability tester is used, then all equipment from 4.1.1 to 4.1.8 is provided as a complete set.

6. Recommended operating conditions

• Non-intensified test conditions: oxidation temperature 160℃, oxygen flow rate 200±10 mL/min, oxidation time 6 h.
• Intensified test conditions: oxidation temperature 165℃, oxygen flow rate 200±10 mL/min, oxidation time 12 h, used for internal combustion engine oils with relatively good oxidation stability.
• The outlet of the oxygen inlet tube is at a distance of 3~4 mm from the bottom of the oxidation tube (see 7.1).
• Oxygen is preliminarily passed at room temperature through a gas washing bottle containing distilled water; the outlet of the gas inlet tube in the gas washing bottle is at a distance of 50 mm from the water surface (see 7.2).
• Transmittance measurement: dilute the sample with petroleum ether at four times the sample mass, use the diluent petroleum ether as reference, and measure at a wavelength of 650 nm using a 1 cm colorimetric cell (see 6.4).
• Centrifugal separation: 1500 r/min, 20 min (see 7.7).

7. Sampling and sample preparation

• 6.3 The kinematic viscosity at 50℃ of the sample before oxidation is determined in accordance with GB/T 265.
• 6.4 Measure the transmittance of the sample before oxidation using a 72 type spectrophotometer; during measurement, dilute the sample with petroleum ether at four times the sample mass, use the diluent petroleum ether as reference, and measure the transmittance of the diluted sample at a wavelength of 650 nm using a 1 cm colorimetric cell.
• Sampling amount: inject the sample into a clean, dry oxidation tube up to the 40 mL graduation line (see 7.1).
• Other sampling requirements: not provided in the available source.

8. Analytical procedure

• 6.1 Washing of the oxidation tube, oxygen inlet tube, metal sheet hanging sleeve, and centrifuge tube: wash with solvent or chromic acid cleaning solution, then rinse with water, finally rinse clean with distilled water, and dry.
• 6.2 Treatment of metal sheets:
  • 6.2.1 Lead sheet: scrub with laundry detergent powder or soak in 13% (m/m) hydrochloric acid solution for 15~20 min until the surface oxide layer is removed, then rinse clean under running water, blot dry with filter paper, and polish bright with chamois leather; during the treatment process, take care not to produce a new oxide layer.
  • 6.2.2 Copper sheet and iron sheet: carefully grind longitudinally with 500 grade and 700 grade sandpaper successively until smooth and bright, with no obvious machining marks.
  • 6.2.3 Wipe the ground and polished metal sheet with absorbent cotton in a vessel containing ethanol-benzene mixed liquid until the solvent used to wash the metal sheet leaves no stain on the filter paper (replace the solvent at least once). Finally, blot dry with filter paper, place in a desiccator, and use within 24 h. When handling metal sheets, always use bamboo tongs; direct contact with hands is not allowed. In the subsequent steps, direct contact with hands is also not allowed.
  • 6.2.4 After treatment, the copper sheet and lead sheet are weighed to an accuracy of 0.0002 g.
• 7.1 Inject the sample into a clean, dry oxidation tube up to the 40 mL graduation line. Hang the treated copper sheet (already weighed), lead sheet (already weighed), and iron sheet on the metal sheet hanging sleeve, place the metal sheet hanging sleeve on the protruding part of the oxygen inlet tube, and place them in the sample in the oxidation tube so that the oxygen inlet tube is fixed at the center of the oxidation tube, with the outlet of the oxygen inlet tube at a distance of 3~4 mm from the bottom of the oxidation tube.
• 7.2 Place the oxidation tube containing the sample and metal sheets into a constant-temperature bath that has reached the specified temperature, and introduce oxygen at a rate of 200±10 mL/min; the oxygen must first pass at room temperature through a gas washing bottle containing distilled water, so that the outlet of the gas inlet tube in the gas washing bottle is at a distance of 50 mm from the water surface.
• 7.3 When oxygenation has proceeded to 5.5 h, place a piece of blue litmus paper moistened with distilled water at about 30 s from the mouth of the oxidation tube, and record the color change of the blue litmus paper.
• 7.4 When oxidation has proceeded to the specified time, turn off the power and oxygen, and remove the oxidation tube from the constant-temperature bath.
• 7.5 Remove the metal sheets from the oxidation tube, and take 5 mL of the oxidized sample into a 50 mL centrifuge tube for the n-pentane insolubles test. First roughly wash the metal sheets in solvent naphtha once or twice, then wipe them two to three times with absorbent cotton in a vessel containing ethanol-benzene mixed liquid until the loose oxide on the surface is removed, but take care not to scratch the metal sheets, and finally blot dry with filter paper.
• 7.6 Place the washed copper sheet and lead sheet in a desiccator for 30 h, and weigh with an analytical balance to an accuracy of 0.0002 g.
• 7.7 Within 30 h, add 45 mL n-pentane to the centrifuge tube already containing 5 mL of the oxidized sample and stir evenly, then centrifuge in a centrifuge at 1500 r/min for 20 min, and record the volume of the precipitate, which is the amount of n-pentane insolubles in the sample.
• 7.8 After oxidation, the sample is tested within 30 h, according to GB/T 265, to determine its 50℃ kinematic viscosity.
• 7.9 After oxidation, the sample is tested within 30 h, according to clause 6.4, to determine its light transmittance.

9. Qualitative and Quantitative Determination and Calculation Formulas

The oxidation stability of the sample is calculated as the sum of the scores of six individual indicators. The scores of the six individual indicators are calculated according to their respective specified calculation standards.

• 8.1.1 Copper strip score X is calculated according to formula (1):
  • X = X₁ / 1
  • Where: X₁ — copper strip weight loss or weight gain, mg; 1—— calculation standard, mg.
  • (The original formula is typeset as "•(1)"; the specific symbol requires confirmation against the source standard (source-text extraction))
• 8.1.2 Lead strip score Y is calculated according to formula (2):
  • Y = Y₁ / 10
  • Where: Y₁ — lead strip weight loss or weight gain, mg; 10—— calculation standard, mg.
• 8.1.3 50℃ kinematic viscosity score Z is calculated according to formula (3):
  • Z = Z₁ / 5
  • Where: Z₁ — 50℃ kinematic viscosity increase rate, %; 5—— calculation standard, %.
  • 50℃ kinematic viscosity increase rate Z₁ (%) is calculated according to formula (4):
    • Z₁ = (ν₁ / ν₀) × 100
    • Where: ν₁ — kinematic viscosity of the sample after oxidation 50℃, mm²/s; ν₀ — kinematic viscosity of the sample before oxidation 50℃, mm²/s.
    • (The original formula is typeset as "2.= ”×100"; the symbol requires confirmation against the source standard (source-text extraction))
• 8.1.4 Color score E is calculated according to formula (5):
  • E = E₁ / 30
  • Where: E₁ — difference in light transmittance of the sample before and after oxidation; 30—— calculation standard.
  • (The original formula is typeset as "B- box"; the symbol requires confirmation against the source standard (source-text extraction))
• The calculations in the above formulas are accurate to two decimal places.
• 8.1.5 n-Pentane insolubles score: scoring is performed only when the n-pentane insolubles after oxidation reach and exceed 0.1%. 0.1% counts as 5 points, and for each increase of 0.1%, 1 points are added.
• 8.1.6 Acidity/alkalinity score of the sample vapor: when the oxidation test proceeds to 5.5 h, check the sample vapor with moist blue litmus paper according to clause 7.3. If the litmus paper turns red, it is acidic, and 3 points are counted; if it does not change color, it is alkaline, and zero points are counted.

10. Precision

Repeatability: For samples with a total score below 50 points, the difference between two results of repeated determinations by the same operator and their arithmetic mean shall not exceed 15% of their arithmetic mean. (The source wording for the results and comparison is unclear; verify this repeatability requirement against the original standard)

11. Report

Take the arithmetic mean of two results of repeated determinations as the determination result of the oxidation stability of internal combustion engine oils.

12. Referenced Documents

• GB/T 265 Petroleum products — Determination of kinematic viscosity and calculation of dynamic viscosity

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A