SH/T 0708-2001 Method for Evaluating the Detergency and General Performance of Water-Cooled Two-Stroke Gasoline Engine Oils (OMC 70HP Method)

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Card type: Test method

1. Method Number / Full Title / English Name / Replacement Relationship

• Standard number: SH/T 0708-2001
• Chinese full title: Method for Evaluating the Detergency and General Performance of Water-Cooled Two-Stroke Gasoline Engine Oils (OMC 70HP Method)
• English name: Standard test method for evaluating detergency and general performance of water-cooled two-stroke gasoline engine oil (OMC 70HP)
• Replacement relationship: not provided in the available source (the foreword only states equivalent adoption of NMMA "OMC 70HP test procedure (TC-W3)", and does not mention replacement of an old standard)
• Publication/implementation: published on 2001-11-23, implemented on 2002-01-01; issuing body: State Economic and Trade Commission
• Administering body: Sinopec Research Institute of Petroleum Processing
• Drafting body: Research Institute of Maoming Branch, Sinopec Corp.
• Main drafters: Liang Qirui, Lin Yuesheng, Feng Xinping, Zhou Weizheng, Tang Tao, Zeng Yanjie

2. Scope of Application and Non-Application

• This standard specifies the method for evaluating the detergency and overall performance of water-cooled two-stroke gasoline engine oils.
• It is applicable to evaluating the detergency and general performance of water-cooled two-stroke gasoline engine oils used in water-cooled two-stroke gasoline engines such as outboard motors.
• Not applicable: not provided in the available source.

3. Method Principle

A modified OMC 920 mL displacement two-stroke outboard motor is used in a test water tank to conduct comparative tests with a reference oil and a sample oil successively on the same outboard motor. Under specified operating conditions, the engine is first run in for 2 h, then operated at idle for 5 min and at wide-open throttle for 55 min; this cycle is repeated 98 times, that is, operation for 98 h. Finally, by comparing the evaluation results of the reference oil and the sample oil, the detergency of the sample oil, piston ring sticking caused by the sample oil, and other performance are evaluated.

4. Reagents and Materials (Purity / Preparation)

• 6.1 Test fuel: use specially blended TC-W3 ring sticking fuel, with physical and chemical indicators given in Annex B Table B1. Each engine test requires about 2800 L of fuel.
• 6.2 Reference oil: grade NMMA 93738, required amount per test 57 L.
• 6.3 Sample oil: required amount per test 57 L.
• 6.4 Gear oil: each test requires about GL-5 gear oil 0.4 L (the original text at source-text extraction reads "each test requires GI-5 [garbled calibration-oil wording]i t 0.41", requires confirmation against the source standard (source-text extraction)).
• 7.2 Mixed fuel preparation: according to the mixing ratio 50:1 (volume ratio), mix the TC-W3 ring sticking fuel meeting the requirements of Annex B Table B1 separately with the sample oil and the reference oil to prepare about 2744 L of mixed fuel.

5. Instruments and Equipment

• 5.1 Test engine: OMC Johnson BJ70 TLECB model or equivalent outboard motor, with main technical parameters given in Annex A Table A1.
• 5.2 Engine modification:
  • 5.2.1 Remove the original propeller and use a load wheel (OMC part number 386665) as the power absorption device; after machining, it must maintain the speed at wide-open throttle at 5000 r/min ± 200 r/min.
  • 5.2.2 Plug the oil pump suction inlet of the original engine (because premixed fuel is used).
  • 5.2.3 Change the cooling system to two separate systems: midsection cooling system and powerhead cooling system.
    • 5.2.3.1 Midsection cooling system: install an aluminum gasket with thickness 0.5 mm～0.6 mm between the midsection and the powerhead (Annex F Figure F1); modify the water pump outlet pipe as shown in Annex F Figure F2; midsection cooling is accomplished by the original engine water pump using water from the test water tank.
    • 5.2.3.2 Powerhead cooling system: install a water pipe connector at the exhaust side cover (Annex F Figure F3), and install an inlet water temperature thermocouple connector at 50 mm from the connector; install a water pipe connector on the cylinder head (Annex F Figure F4), and install an outlet water temperature thermocouple connector at 50 mm from the connector; powerhead cooling water is supplied by circulation from a water pump with water pressure about 200 kPa and displacement about 250 L/min, and the water temperature is regulated through a heat exchanger.
• 5.3 Test water tank: with sufficient ventilation, sufficient volume, and necessary buffers installed; with water inlet, drain outlet, and overflow outlet; establish an exhaust ventilation system to remove exhaust gas.
• 5.4 Fuel system: supplied by fuel pump, with high-level fuel supply; mixed fuel passes from the fuel tank through the filter, fuel consumption meter, and outboard motor connector to the fuel pump; when stopped, the fuel pressure at the fuel pump suction inlet must not exceed 35 kPa.
• 5.5 Instruments and meters:
  • 5.5.1 Spark plug gasket: made of copper, thickness 1.8 mm～2.2 mm, outer diameter 20.8 mm～21 mm, inner diameter 14.3 mm～14.6 mm; drill two holes of diameter 1 mm radially in the middle of the gasket, with a spacing of about 5 mm between the two holes, and braze the temperature-measuring thermocouple with silver.
  • 5.5.2 Spark plug gasket temperature recorder: capable of continuous signal scanning and alarming, recording and displaying instantaneous parameter changes and the entire test change process, with maximum interval less than 2 s and accuracy of 1 ℃.
  • 5.5.3 Temperature recorder: coolant inlet and outlet temperature 0 ℃～200 ℃; intake air temperature 0 ℃～200 ℃; ambient temperature 0 ℃～100 ℃; spark plug gasket temperature 0 ℃～400 ℃; accuracy for all is ±1 ℃.
  • 5.5.4 Tachometer: accurate to ±25 r/min.
  • 5.5.5 Fuel flow meter: accuracy at flow rate 18 kg/h is ±0.09 kg/h; a mass flow meter is recommended, and its accuracy must be calibrated.
  • 5.5.6 Timing light: a timing light for a high-energy ignition system with speed measurement and advance angle measurement.
  • 5.5.7 Barometer: measuring range 31 kPa～110 kPa, accuracy ±0.1 kPa.
  • 5.5.8 Hygrometer: ordinary hygrometer.

6. Recommended Operating Conditions

• Break-in: start the engine and run at 1000 r/min ± 100 r/min for 10 min; increase speed to 5000 r/min ± 200 r/min, adjust ignition timing to 19°(BTDC); then run according to 3000 r/min ± 200 r/min for 1 h, and run at 4000 r/min ± 200 r/min for 1 h; the cooling water outlet temperature shall not be higher than 60 ℃ (the original text at source-text extraction reads "[unreadable value]℃", requires confirmation against the source standard (source-text extraction)). After break-in, retighten the top bolts to 24 N·m～27 N·m. Break-in must be carried out with the test oil.
• Formal test conditions (Table 1):
  • Wide-open throttle (W.O.T): speed 5000 r/min ± 200 r/min; fuel consumption rate 18.0 kg/h ± 0.23 kg/h (note); ignition timing (BTDC) 19°±1°; cooling water outlet temperature 54 ℃±2 ℃; cooling water inlet temperature recorded; cooling water inlet-outlet temperature difference 17 ℃±2 ℃.
  • Idle: speed 1000 r/min ± 100 r/min; fuel consumption rate recorded; ignition timing recorded; cooling water outlet temperature recorded; cooling water inlet temperature recorded; cooling water inlet-outlet temperature difference recorded.
  • Note: this value is based on the fuel consumption during the discriminating test between high/low reference oils, with allowable deviation ±0.23 kg/h; the sample oil must be run under the same conditions as the reference oil; in the same procedure, the reference oil and all sample oils should target the same given value.
• Test cycle: 5 min idle + 55 min wide-open throttle (W.O.T) is one cycle, repeated for 98 cycles, totaling 98 h; total test time including break-in is 100 h.
• Shutdown inspection conditions: if the speed at wide-open throttle changes by more than ±200 r/min or more, the engine should be shut down for inspection; if the spark plug temperature changes suddenly, the engine should also be shut down to investigate the cause.

7. Sampling and Sample Preparation

• 7.1 Engine assembly:
  • 7.1.1 Replace with new piston, piston rings, spark plug, connecting rod bearings, and seal components for each test; clean parts with solvent oil, replace damaged parts, and if necessary replace the entire short block or even the entire engine.
  • 7.1.2 Measure the cylinder diameter along two directions parallel and perpendicular to the crankshaft: 19.0 mm below the cylinder top; 76.2 mm below the cylinder top. Cylinder roundness shall not be greater than 0.08 mm, cylindricity shall not be greater than 0.05 mm; cylinder inner surface roughness 0.51 μm～1.02 μm (the original text at source-text extraction reads "0.51psn[unreadable separator]1.02pm", requires confirmation against the source standard (source-text extraction)); the cylinder inner surface must not be honed; if it is unqualified or rusted and cannot be wiped off with reference oil, the powerhead should be replaced.
  • 7.1.3 Measure the piston diameter along the piston pin in both parallel and perpendicular directions at the top ring land and at 6.35 mm upward from the bottom of the piston skirt.
  • 7.1.4 Piston-to-cylinder clearance: clearance at the top ring land and at 19 mm below the top of the cylinder is 0.58 mm～0.66 mm; clearance between the upper part of the piston skirt and the upper part of the cylinder exhaust port is 0.10 mm～0.15 mm.
  • 7.1.5 Piston ring end gap: place the piston ring at 19 mm below the top of the cylinder and measure; the requirement is 0.18 mm～0.43 mm.
  • 7.1.6 Compression ratio: the compression ratio of each cylinder should be within 6.2:1～6.8:1.
  • 7.1.7 Assemble the engine according to outboard motor requirements.
• 7.2 Test fuel preparation: mix separately with the sample oil and reference oil at a mixing ratio of 50:1 (volume ratio) to prepare approximately 2744 L of blended fuel.
• 7.3 Before a new engine, an engine with a replaced powerhead, or an engine after major repair is used for sample oil evaluation, it should be calibrated with NMMA 93738 and NMMA 32299 oil; the calibration results should meet the requirements of Appendix E.

8. Analysis Procedure

• 8.1 Break-in and ignition timing adjustment: start the engine and run at 1000 r/min ± 100 r/min for 10 min; increase speed to 5000 r/min ± 200 r/min, adjust the ignition timing to 19°(BTDC); then run according to 3000 r/min ± 200 r/min for 1 h, and run at 4000 r/min ± 200 r/min for 1 h; the cooling water outlet temperature shall not exceed 60 ℃ (requires confirmation against the source standard (source-text extraction)). After break-in, retighten the top bolts to 24 N·m～27 N·m; break-in must be carried out with test oil.
• 8.2 Formal test:
  • 8.2.1 Test cycle: 5 min idle + 55 min wide-open throttle (W.O.T) is one cycle, repeated for 98 cycles, totaling 98 h; total test time including break-in is 100 h. Formal test conditions are shown in Table 1.
  • Troubleshooting: if the speed changes by more than ±200 r/min or more at wide-open throttle, stop the engine and inspect; if the spark plug temperature changes suddenly, also stop the engine and investigate the cause; when it is determined that the spark plug is not firing, remove the spark plug and record its condition, record the number of failure hours, replace with a new spark plug, and continue the test after eliminating the fault; if the piston assembly, cylinder head, connecting rod bearing, or the entire short block must be replaced due to a fault, the test results are invalid; if the test cannot continue due to sample oil quality problems, terminate the test and explain in the report.
  • After the reference oil test is completed, the sample oil test should be carried out immediately.
  • 8.2.2 Test data recording:
    • Coolant inlet temperature, outlet temperature, spark plug gasket temperature: record once at 5 min before each idle cycle.
    • Wide-open throttle (W.O.T) speed: record 1 times each at 5 min before each idle cycle and at 5 min after each idle cycle.
    • Idle speed: record 1 times per idle cycle.
    • Fuel flow: record 1 times at 5 min before each idle cycle.
    • Ambient temperature: record 1 times at 5 min before each idle cycle.
    • Coolant inlet pressure: record 1 times at 5 min before each idle cycle.
    • Wide-open throttle (W.O.T) ignition timing: record 1 times every 7 h.
    • Idle ignition timing: record 1 times every 7 h.
    • Atmospheric pressure: record 1 times every 4 h.
    • Wet-bulb and dry-bulb temperatures: record 1 times every 4 h.

9. Qualitative and Quantitative Evaluation and Calculation Formulas

• 9.1 After the test ends, disassemble the engine within 2 h～12 h, and evaluate the test results within 24 h. The order is: disassembly, piston ring sticking scoring, photographing relevant components, scoring and evaluation of specified components. For the cleanliness and general performance scoring method, see Appendix C.
• 9.2 Compare the sample oil evaluation results with the reference oil results, issue a test result report in the format of Appendix D Table D1, and attach photographs of the relevant test components.
• Appendix C Scoring Method:
  • C2.3 Piston ring scoring: free ring 10 points; dull ring 9.5 points; spot-stuck ring or tight ring 9.0 points; cold-stuck ring 9.0 points～5.0 points; hot-stuck ring 4.0 points～0 points.
    • Standard ring cold sticking merit score = 9.4 − (ring cold sticking angle × 0.01333) ………………(C1)
      • Note: The formula is suitable for ring cold sticking angles from 30°～330°; for less than 30°, the merit score is 9.0 points; for greater than 330°, the merit score is 5.0 points.
    • Ring hot sticking merit score = 4.4 − (ring hot sticking angle × 0.01333) ………………(C2)
      • Note: For hot sticking angles less than 30°, the merit score is 4.0 points; for greater than 330°, the merit score is 0 points.
    • The arithmetic average of the visual cold sticking score and the standard cold sticking score is the corrected cold sticking score of the ring.
  • C2.4 Piston lacquer film scoring: determine the severity coefficient and area percentage according to the CRC No. 14 lacquer film standard color plates; the coefficient for the most severe deposit is 1.0, and the coefficients for black lacquer film and all carbon deposits are 1.0.
    • Piston lacquer film scoring locations: A) piston top ring land; B) piston second ring land; C) piston skirt; D) piston inner top. Each location has a full score of 10 points.
    • Total merit score = Σ( severity coefficient × area %) ………………(C3)
  • C2.5 Piston carbon deposit scoring: the clean surface coefficient is 10; for lacquer film, the coefficient determined by severity grade divided by 10 plus 9.0 is the deposit severity coefficient; for carbon deposits, the coefficient is determined by thickness (Table C3).
    • Table C3 Deposit severity coefficient: 10 clean; 9.9～9.0 lacquer film (according to SH/T 0510 color grade, deposit severity coefficient = 9.0 + lacquer film severity coefficient/10); 9.0 carbon deposit with thickness less than 0.1 mm; 8.0 0.1 mm ≤ thickness < 0.2 mm; 7.0 0.2 mm ≤ thickness < 0.3 mm; 6.0 0.3 mm ≤ thickness < 0.4 mm; 5.0 0.4 mm ≤ thickness < 0.8 mm; 4.0 0.8 mm ≤ thickness < 1.6 mm; 3.0 1.6 mm ≤ thickness < 3.2 mm; 2.0 3.2 mm ≤ thickness < 6.4 mm; 1.0 6.4 mm ≤ thickness < 12.8 mm; 0 thickness is 12.8 mm or more.
    • Carbon deposit scoring locations: A) piston top; B) cylinder head; C) exhaust port blockage; D) exhaust passage blockage. Each location has a full score of 10 points; blockage scoring: 0% clean is 10 points, 100% fully blocked is 0 points.
  • C2.6 Component appearance condition evaluation: evaluate discoloration of the piston pin, connecting rod small end bearing, connecting rod small end bearing seat, crankshaft main bearing, crankshaft main journal, connecting rod big end bearing seat, connecting rod big end bearing, and crankpin; use three standard color plates for rust/lacquer film scoring for comparison, determine the severity coefficient and area percentage, multiply and sum the scores, and the clean area must be included. Each location has a full score of 10 points.
  • C2.7 Spark plug deposit condition description: record the condition of the spark plug electrodes, deposits, spark plug gap, etc.; common terms: A) general deposits; B) core bridging; C) spark plug gap bridging; D) spark plug electrode erosion; E) pre-ignition; F) other.
• Appendix E Calibration machine result requirements:
  • Corrected second ring sticking average score: NMMA 93738 5.1 points ≤ score ≤ 7.5 points; NMMA 32299 score ≥ (0.537 × NMMA 93738 score) + 4.4.
  • Average piston deposit score: NMMA 93738 3.2 points ≤ score ≤ 6.4 points; NMMA 32299 score ≥ NMMA 93738 score + 0.5 points.

10. Precision

not provided in the available source.

11. Report

• 9.2 Issue a test result report in the format of Appendix D Table D1, and attach photographs of the relevant test components.
• Appendix D Table D1 Report content: sample name, submitting unit, test method, test date; scoring parts include second ring adhesion score, top ring land, second ring land, piston inner crown, piston skirt, piston outer crown, cylinder head, exhaust port blockage, exhaust passage blockage, spark plug failure, crankcase, conclusion, remarks; reporter, reviewer.
• When the test is terminated due to sample oil quality problems, it should be explained in the test result report (8.2.1).

12. Normative references

• GB/T 380 Determination of sulfur content in petroleum products (lamp method)
• GB/T 503 Determination of gasoline octane number (motor method)
• GB 1922 Solvent naphtha
• GB/T 5096 Copper strip corrosion test method for petroleum products
• GB/T 5487 Determination of gasoline octane number (research method)
• GB/T 6536 Distillation determination method for petroleum products
• GB/T 8017 Determination of vapor pressure of petroleum products (Reid method)
• GB/T 8018 Determination of oxidation stability of gasoline (induction period method)
• GB/T 8019 Determination of existent gum in automotive gasoline and aviation fuels (jet evaporation method)
• GB/T 8020 Determination of lead content in gasoline (atomic absorption spectrometry)
• GB/T 11132 Determination of hydrocarbon types in liquid petroleum products
• GB 17930 Unleaded gasoline for motor vehicles
• SH/T 0510 Engine test scoring method for gasoline engine oils
• SH/T 0647 Evaluation method for preignition tendency of water-cooled two-stroke gasoline engine oils
• SH/T 0648 Evaluation method for cleanliness and general performance of water-cooled two-stroke gasoline engine oils
• SH/T 0657 Determination of trace nitrogen in liquid petroleum hydrocarbons (oxidative combustion and chemiluminescence method)

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 Q&A reference