SH/T 0670-1998 Evaluation of the lubricity of water-cooled two-stroke gasoline engine oils

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SH/T 0670-1998 specifies a test method for evaluating the lubricity of water-cooled two-stroke gasoline engine oils (two-stroke oils) such as those used in outboard motors, using a 49 cm³ air-cooled single-cylinder engine and torque drop measurement.

Evidence note: the content of this page was compiled from the original text of this standard held in the Origin Standard library (points marked "[to be verified]" are "[source unclear]" in the original); for individual values and current status, refer to the original pages of the standard and the product certificate.

Scope: This standard specifies a test method for evaluating the lubricity of water-cooled two-stroke gasoline engine oils (hereinafter referred to as two-stroke oils) such as those used in outboard motors. 1.2 This standard applies to the evaluation of water-cooled two-stroke gasoline engine oils used in water-cooled two-stroke gasoline engines such as outboard motors. 1.3 This standard is not intended to address all safety issues associated with its use; users should establish appropriate safety and protective measures before using this standard and determine the management regulations that apply. Not applicable: not provided in the available material.

Principle: Method summary: a single-cylinder, air-cooled two-stroke gasoline engine of 49 cm³ displacement ([source unclear]) is used, with a mixed fuel of test fuel oil and standard reference oil or sample oil at a volume mixing ratio of 150:1. During the test the engine throttle is fully open and the speed is constant; after stabilization the cooling air is cut off, the engine torque is measured while the spark plug gasket temperature is 200–350 °C, and the torque drop over that interval is recorded. The smaller the torque drop, the better the lubricity of the lubricating oil. Tests with the reference oil and the sample oil are carried out alternately; each group of tests usually comprises 5 tightening runs.

Apparatus: Test engine 5.1.1 A YAMAHA CY50 motorcycle engine is used, specifications in Table 1: | Item | Specification | |---|---| | Motorcycle model | YAMAHA CY50 | | Engine model | 3kJ | | Number of cylinders | 1 | | Bore × stroke | 40×39.2 mm×mm | | Displacement | 49 mL | | Cooling method | Forced air cooling | | Compression ratio | 7.2:1 | | Piston | Aluminium alloy | | Cylinder | Cast iron liner | 5.1.2 Piston clearance adjustment: hone the cylinder so that the bore has an average roughness of 0.45–0.70 μm ([source unclear]); the diametral clearance at the piston skirt is 0.10–0.13 mm, as shown in Annex B. It is recommended to hone a certain number of cylinders, and the adjusted cylinders shall be clearly marked. The test engine shall be provided with the following: (1) an external characteristic curve including power and fuel oil consumption, at 500 r/min intervals over the range 3 000–6 000 r/min; (2) the spark plug gasket temperature at each operating point on the external characteristic curve; (3) the dimensions and clearances of piston and cylinder; (4) the clearance dimensions of the piston rings. 5.2 Dynamometer: torque measurement accuracy ±0.5%; the dynamometer absorbs 2.5 kW at 4000 r/min. When its power input is changed, the dynamometer can still maintain an operating speed of 4000 r/min±30 r/min ([source unclear]); the dynamometer may be driven directly by the engine or through a belt drive. 5.3 Cooling system: remove the cooling fan from the engine and cool the engine with an external blower. The blower air volume shall be at least 34 m³/min ([source unclear]), ducted to the front of the engine, and the cooling air flow shall be adjustable. 5.4 Fuel oil system: the fuel oil pressure before entering the carburettor shall be maintained at 19–21 kPa and the fuel oil temperature shall not exceed 30 °C; if the temperature is too high, cooling shall be applied. This test usually requires three fuel oils: a mixture of sample oil and test fuel, a mixture of reference oil and test fuel, and test fuel without lubricating oil. 5.5 Engine temperature measurement 5.5.1 Spark plug gasket thermocouple: a K-type thermocouple is fitted in a copper spark plug gasket, construction as shown in Annex E, measurement accuracy ±1%. 5.5.2 Exhaust temperature thermocouple: a sheathed K-type thermocouple 150 mm long and 3 mm in diameter is used to measure the exhaust temperature, installed about 65 mm from the cylinder exhaust port, at ±3 mm from the centre of the exhaust pipe. 5.5.3 Temperature display and recording instrument: the display and recording interval for the spark plug gasket temperature shall not exceed 1 s, and for the exhaust temperature not exceed 10 s; the accuracy of the display and recording instrument is ±1 °C. 5.6 Instruments and meters: a computer is used to acquire, process and plot data such as spark plug gasket temperature, engine torque and engine speed. Alternatively, an X-Y recorder is used to record the spark plug gasket temperature and engine torque, and the torque drop value is determined from the recorded curve. 5.6.1 Tachometer: accuracy ±10 r/min. 5.6.2 Thermometer: accuracy ±1 °C, used to measure the laboratory temperature. 5.6.3 Barometer: accuracy ±0.1 kPa, used to measure the atmospheric pressure in the laboratory. 5.6.4 Hygrometer: a hygrometer of accuracy ±5%, or dry- and wet-bulb thermometers of accuracy ±1 °C, used to measure the laboratory humidity.

Reagents and reference materials: Fuel: the main properties of the test fuel are given in Table 2. | Property | Limit | Test method | |---|---|---| | Octane number (research method) | 89–93 | GB/T 5487 | | Tetraethyl lead | not more than 0.001 g/L | GB/T 8020 | | Distillation 10% evaporated temperature | not more than 70 °C | GB/T 6536 | | Distillation 50% evaporated temperature | not more than 110 °C | GB/T 6536 | | Distillation 90% evaporated temperature | not more than 167 °C | GB/T 6536 | | Final boiling point | not more than 75 °C ([to be verified] ([source unclear]), the final boiling point value is suspected to be erroneous) | GB/T 6536 | | Reid vapour pressure (37.8 °C) | not more than 4 kPa ([to be verified] ([source unclear])) | GB/T 8017 | | Existent gum | not more than 4 mg/100 mL ([to be verified] ([source unclear])) | GB/T 8019 | | Sulfur content | not more than 0.03% (m/m) | GB/T 380 | | Hydrocarbon group composition — olefins | 5–25% (V/V) | GB/T 11132 | | Hydrocarbon group composition — aromatics | 25–35% (V/V) | GB/T 11132 | Note: other determination items shall meet the requirements of SH 0041. 6.2 Sample oil: about 0.4 L is required per test. 6.3 Reference oil: the main properties of the reference oil are given in Annex A. 0.4 L of NMMA 93738 standard reference oil is required per test. A calibration test requires 0.4 L each of calibration oils ASTM 602 and ASTM 604. 6.4 Solvent naphtha: GB 1922 NY-190 solvent naphtha is used. Annex A Main properties of reference oils (Table A1): | Property | NMMA 93738 | ASTM 604 | ASTM 602 | |---|---|---|---| | Kinematic viscosity (40 °C), mm²/s | 34.2–38.2 | not provided in the available material | 107.9 | | Kinematic viscosity (100 °C), mm²/s | 56.6 ([to be verified] ([source unclear])) | not provided in the available material | 12.4 | | Viscosity index | 6.1–6.6 ([to be verified] ([source unclear])) | 114 | 106 | | Total acid value | 8.2 ([to be verified] ([source unclear])) | 0 | 0.9 | | Total base value | 128 ([to be verified] ([source unclear])) | 0.58 | 5.7 | | Sulfated ash | 1.7 ([to be verified] ([source unclear])) | 0 | 0.75 | | Calcium content | 6.5 ([to be verified] ([source unclear])) | 0.40 | 2.5 | | Nitrogen content | <0.005 ([to be verified] ([source unclear])) | <0.005 | 0.02 | | Approximate composition: 150 bright stock | 9.00 | 0 | 60 | | Approximate composition: 650 neutral oil | 61.65 | 72.55 | 0 | | Approximate composition: 650 neutral oil | 20 | 20 | 0 | | Approximate composition: Stoddard solvent | 9.35 | 0 | 20 | | Approximate composition: additives | 7.45 ([to be verified] ([source unclear]), the correspondence between the columns is suspected to be misaligned) | 7.45 ([to be verified] ([source unclear])) | 2 ([to be verified] ([source unclear])) | Test methods: GB/T 265, GB/T 1995, GB/T 7304, SH/T 0251, GB/T 2433, SH/T 0270, SH/T 0244 Additive notes: 1) mainly ashless dispersants; 2) mainly metallic detergents

Key conditions: With the engine at full throttle, a speed of 4000 r/min and a spark plug gasket temperature of 169–171 °C, run steadily for 20–30 min to establish thermal equilibrium. At this point the engine output power shall not be less than 1.4 kW. Cut off the cooling air; when the spark plug gasket temperature rises to 200 °C, start recording the engine torque and continue until the spark plug gasket temperature reaches 350 °C, which completes one tightening run. After cooling, bring the spark plug gasket temperature back to 169–171 °C, run steadily for 3–4 min, cut off the cooling air and repeat the above test procedure. While the cooling air is cut off, the engine shall be protected from draughts. To ensure good repeatability, tests shall be carried out at an ambient temperature of 23–30 °C. One group of tests comprises 5 tightening runs; under the conditions of 8.3, up to 7 tightening runs may be included. 8.2 Run two groups of tests, reference oil and sample oil, in the order of Table 4; the test procedure for each oil shall not be interrupted. The shutdown time between the two oils shall not exceed 1 h, otherwise the whole test shall be repeated. Table 4 Test run sequence: | Tightening data No. | Oil | Group No. | |---|---|---| | 1–5 | Standard reference oil | 1 | | 6–10 | Sample oil | 2 | | 11–15 | Standard reference oil | 3 | | 16–20 | Sample oil | 4 | 8.3 Range of torque drop: for the 5 tightening runs of a group, compare the torque drop values; if the difference between the maximum and minimum values, i.e. the range of torque drop, exceeds 0.085 N·m, repeat one tightening run to replace the one outside the torque drop range; if after one replacement the range of torque drop still exceeds 0.085 N·m, replace one more. A group of tests comprises at most 7 tightening runs. If, after removing two of the 7 tightening runs, the range of torque drop still exceeds 0.085 N·m, reassemble the engine and repeat the test. 8.4 After completing one group of tests, drain the mixed fuel from the carburettor and replace or clean the fuel lines. Before the next group of tests, run the engine at no load at 4000 r/min for 5 min with test fuel containing no lubricating oil, then drain the fuel oil from the carburettor, change to the other mixed fuel oil and carry out the next group of tests in accordance with 8.1. 8.5 Abnormal engine conditions: if the spark plug operates abnormally during the test, replace the spark plug and continue the test, and repeat the test of the group in which the fault occurred. After the test, check that ring sticking and scuffing are absent.

Calculation and results: Pass–fail criterion: if the mean torque drop of the sample oil is less than or equal to the mean torque drop of the standard reference oil, i.e. ΔMₙ ≤ ΔMᵣ, the sample oil passes. Annex C Checking and calculation of data: C1 Checking for outliers: ΔMᵣ = ΣΔMᵣᵢ/nᵣ (C1) ΔMₙ = ΣΔMₙᵢ/nₙ (C2) Bᵣ* = √[Σ(ΔMᵣᵢ − ΔMᵣ)²/(nᵣ−1)] (C3, [to be verified] ([source unclear]), the form of the formula is suspected to be erroneous) Bₙ* = √[Σ(ΔMₙᵢ − ΔMₙ)²/(nₙ−1)] (C4, [to be verified] ([source unclear]), the form of the formula is suspected to be erroneous) where: ΔMᵣᵢ, ΔMₙᵢ—torque drop value of the i-th tightening run of the reference oil and sample oil, i = 1, 2, up to n (or nₙ); ΔMᵣ, ΔMₙ—mean torque drop of the reference oil and sample oil; nᵣ, nₙ—number of valid tightening runs of the reference oil and sample oil. Compare the calculated Bᵣ* and Bₙ* with B_crit obtained from Table C1, at a confidence level of 90% and with nᵣ or nₙ degrees of freedom. If B* ≥ B_crit, the data satisfying |ΔMᵣᵢ − ΔMᵣ|max or |ΔMₙᵢ − ΔMₙ|max are outliers, are invalid and shall be discarded, nᵣ or nₙ is reduced by 1, and the outlier test is continued on the remaining data. If outliers are still present after discarding 2 outliers, the test results are invalid. C2 Equivalence test: Sᵣ = √[Σ(ΔMᵣᵢ − ΔMᵣ)²/(nᵣ−1)] (C5) Sₙ = √[Σ(ΔMₙᵢ − ΔMₙ)²/(nₙ−1)] (C6) S_pc = √[((nᵣ−1)Sᵣ² + (nₙ−1)Sₙ²)/(nᵣ+nₙ−2)] (C7) t' = |ΔMᵣ − ΔMₙ|/[S_pc √(1/nᵣ + 1/nₙ)] (C8) where: Sᵣ, Sₙ—standard deviations of the reference oil and sample oil; S_pc—pooled standard deviation of the reference oil and sample oil. If t' ≤ t_crit, the mean torque drops of the two oils are equivalent; otherwise they are not equivalent, i.e. there is a significant difference. C3 Calculation example: C3.1 Test torque drop values (N·m): Standard reference oil: 0.275, (0.336), 0.258, 0.249, 0.244, 0.260 Sample oil: 0.264, 0.251, 0.263, 0.247, 0.256 Standard reference oil: 0.262, 0.248, 0.268, 0.272, 0.248 Sample oil: 0.263, 0.259, 0.267, 0.270, 0.265 C3.2 In the first group it is evident that the range of torque drop has exceeded 0.085 N·m; in accordance with 8.2.3, one additional tightening run is added to replace 0.336 (the clause number cited in the original is "8.2.3", [to be verified] ([source unclear]); the corresponding clause in the text is 8.3). C3.3 Reference oil: ΔMᵣ = 0.258 4, Sᵣ = 0.010 96; sample oil: ΔMₙ = 0.260 5, Sₙ = 0.007 25. C3.4 S_pc = 0.0093, t' = 0.517; from Table C2, t_crit = 1.734. t' < t_crit, i.e. the mean torque drops of the two oils are considered not significantly different; the mean torque drop of the sample oil equals that of the standard reference oil, and the sample oil passes. Table C1 Distribution of B_crit values (confidence levels 90%, 95%, 99%, 99.9%; degrees of freedom 5–25): specific values are listed in the original and are omitted here ([to be verified] ([source unclear]), some values are suspected to be misaligned). Table C2 Distribution of t_crit values (confidence levels 90%, 95%, 99%, 99.9%; degrees of freedom 10–30): specific values are listed in the original and are omitted here ([to be verified] ([source unclear]), some values are suspected to be misaligned).

Normative references: GB/T 265 Petroleum products — Determination of kinematic viscosity and calculation of dynamic viscosity GB/T 380 Petroleum products — Determination of sulfur content (lamp method) GB 1922 Solvent naphtha GB/T 1995 Petroleum products — Calculation of viscosity index GB/T 2433 Petroleum products and additive-containing lubricating oils — Determination of sulfated ash GB/T 5487 Gasoline — Determination of octane number (research method) GB/T 6536 Petroleum products — Determination of distillation GB/T 7304 Petroleum products and lubricants — Determination of neutralization value (potentiometric titration method) GB/T 8017 Petroleum products — Determination of vapour pressure (Reid method) GB/T 8019 Motor gasoline and aviation fuels — Determination of existent gum (jet evaporation method) GB/T 8020 Gasoline — Determination of lead content (atomic absorption spectrometry) GB/T 11132 Liquid petroleum products — Determination of hydrocarbon types (fluorescent indicator adsorption method) SH 0041 Unleaded motor gasoline SH/T 0244 Determination of ammonia content in petroleum additives SH/T 0251 Petroleum products — Determination of base number (perchloric acid potentiometric titration method) SH/T 0270 Determination of calcium content in additives and additive-containing lubricating oils Citation note: the provisions of the following standards, through reference, constitute a part of this standard. Unless otherwise expressly specified in the standard, the referenced standards below shall be the currently valid editions.

Evidence note: [to be verified] and [source unclear] mark specific points that still require checking against the original text of the standard and do not indicate that they have been verified. Do not use these values or steps directly as a basis for work.

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