SH/T 0575-1993 L-ERB Two-Stroke Gasoline Engine Oil Evaluation Method

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.

Incomplete source card: Sections 13, 14 are absent from the available source. Only available content is translated; source completion is pending.

Card type: Test method

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

• Standard number: SH/T 0575-93
• Chinese name: L-ERB Two-Stroke Gasoline Engine Oil Evaluation Method
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Issuance/implementation: approved by China Petrochemical Corporation 1993-08-19, implemented on 1994-05-01
• Reference adoption: European Coordination Committee standard CEC L-21-T-77 "Evaluation of Two-Stroke Engine Lubricating Oils"
• Custodianship: technical custodianship by the Research Institute of Petroleum Processing
• Drafting: drafted under the responsibility of Tianjin Internal Combustion Engine Research Institute; main drafters Dong Shiqiang, Xie Shiwen, Gong Yuying

2. Scope of application and non-applicability

• This standard specifies the engine evaluation method for high-temperature lubricity, general deposits, and pre-ignition resistance of L-ERB two-stroke gasoline engine lubricating oils.
• Products evaluated and passed by this standard are applicable to air-cooled two-stroke gasoline engines of medium load (liter power below 73kW/L) and medium displacement (around 125mL). These gasoline engines are mainly used as land motorcycle engines.
• Not applicable: not provided in the available source.

3. Method principle

This standard includes three evaluation procedures:

• Procedure 1: high-temperature lubricity test
• Procedure 2: general deposits test
• Procedure 3: pre-ignition test

4.1 High-temperature lubricity test When the engine operates under maximum load conditions, the temperatures of the piston and cylinder block are too high; under conditions of high temperature and high surface pressure, the lubricating oil is not easy to maintain an oil film. To evaluate the ability of the lubricating oil to resist scuffing and seizure, the high-temperature lubricity test method is used for assessment. The engine operates stably under specified operating conditions; adjust the cooling air so that the spark plug gasket temperature stabilizes at 170℃, then cut off the cooling air. The dynamometer is set to constant speed to ensure the engine operates at constant speed. Record the torque decrease value as the spark plug gasket temperature rises from 190℃ to within the range of 290℃. Calculate the torque decrease value per unit time within the temperature range of the spark plug gasket from 190—290℃. Compare the torque decrease value per unit time of the sample oil with the torque decrease value per unit time of the standard reference oil. Determine whether the lubricity of the test oil is qualified.

4.2 General deposits test Internal engine carbon deposits, especially deposits accumulated on the combustion chamber surfaces and in the exhaust port, can cause a reduction in engine output power. This method is used to evaluate the tendency of lubricating oil to form deposits. The lubricating oil and fuel oil are mixed at a high-concentration volume ratio; the engine is operated according to the specified procedure for 50h, the engine is in a state contaminated by carbon deposits, measure the power values at 8 different speeds with the engine throttle fully open, and calculate the arithmetic mean of the power at 8 points. After disassembling the engine to evaluate the carbon deposit condition, thoroughly clean the engine, reassemble it, and again perform the specification of measuring the power values at 8 different speeds with the throttle fully open; calculate the difference between the two arithmetic mean power values before and after cleaning to obtain the net power loss value caused solely by deposits. The power loss coefficient can evaluate the tendency of lubricating oil to form carbon deposits and can be used to appraise the quality of the lubricating oil.

4.3 Pre-ignition test Due to carbon deposits in the combustion chamber, pre-ignition of the air-fuel mixture is caused; at this time the spark plug gasket temperature rises and the engine output torque decreases, which is considered pre-ignition caused by lubricating oil carbon deposits. For the pre-ignition test, a suitable high-heat-value spark plug and high-octane fuel must be selected to exclude abnormal combustion caused by the spark plug and by the use of low-octane fuel. The time and number of occurrences of pre-ignition during the continuous test time are used as the criteria for evaluating whether the lubricating oil passes the pre-ignition procedure.

4. Reagents and materials (purity / preparation)

• 6.1 Sample oil: each evaluation requires sample oil 25L.
• 6.2 Fuel oil: standard fuel oil; physical and chemical analysis indicators are given in Appendix D.
• 6.3 Reference oil: listed in Table 1.

Table 1 Reference oil names

• 6.4 Cleaning liquid: for cleaning carbon deposits and deposits on the surfaces of the piston and cylinder head combustion chamber after the test, use the cleaning liquid prepared according to Appendix I.
• 6.5 Solvent naphtha: is GB 1922 No. 190 used for cleaning parts.

Appendix D Standard fuel

Table D1

Appendix I Preparation of cleaning liquid

Table I1

5. Instruments and equipment

• 5.1 Test engine: use a NF-125 two-stroke gasoline engine; specific specifications are given in Appendix A.
  • 5.1.1 Connection of the engine transmission system: remove the gearbox and clutch; the crankshaft output end is directly connected to the dynamometer main shaft through a flexible coupling.
  • 5.1.2 Carburetor modification: keep the carburetor in a horizontal working position; the original carburetor main metering orifice flow is 177mL/min; this method uses main metering orifices of 180 and 195mL/min according to different procedures.
  • 5.1.3 Lubrication system modification: remove the drive gear of the separate lubrication pump, stop the operation of the separate lubrication pump, and change to mixed lubrication.
• 5.2 Engine dynamometer equipment: DC electric dynamometer, model ZDC-9000; detailed specifications and performance are given in Appendix B.
• 5.3 Cooling fan and air duct: 4.5 centrifugal blower, air volume 5730m³/h. Air outlet size 250mm×250mm, connecting hose diameter 250mm. To adjust the air volume, an adjusting gate and a bypass opening need to be added in the air duct.
• 5.4 Exhaust system: use model B30K1-114 explosion-proof axial fan, air volume 3000m³/h; the suction opening faces the engine muffler, so exhaust smoke can be drawn away through the duct in time. Hose diameter 150mm.
• 5.5 Spark plug gasket temperature measurement system: the gasket structure diagram is given in Appendix C.
• 5.6 Exhaust temperature measurement system: use a K type sheathed thermocouple with diameter 3mm and length 150mm, installed at a distance of 50mm from the engine exhaust pipe opening; the end of the thermocouple is at the center of the exhaust pipe cross-section.
• 5.7 Fuel system: the height difference between the bottom of the fuel tank and the oil level in the carburetor float chamber should be maintained between 450mm and 500mm during the test.
• 5.8 Test instruments and meters: specifications are given in Appendix H.

Appendix A Engine specifications for evaluation

Table A1

Appendix B Dynamometer specifications

Table B1

Appendix C Spark plug gasket temperature sensor structure diagram Drill a small hole radially in the gasket, insert the thermocouple junction into the small hole, press the two flat faces of the gasket, and fix the thermocouple in the small hole. The gasket material is copper. Outer diameter 0.3mm nickel-chromium-nickel-silicon K type thermocouple wire is welded firmly to the compensating lead wire. Outer sleeve is a heat-resistant insulating tube.

Appendix H Specifications of test instruments and meters for the evaluation bench

Table H1

6. Recommended operating conditions

High-temperature lubricity test (procedure 1) debugging parameters (8.3.1):

• Speed n = 5000r/min ± 25r/min
• Torque P = 44.1N (4.5kgf)
• Power Nₑ = 4.136kW (5.625PS)
• Fuel consumption rate gₑ = 470g/kW·h ± 20g/kW·h (345g/PS·h ± 15g/PS·h)
• Gasket temperature tₛ = 170—175℃

Deposit test (procedure 2) debugging parameters (9.4.1):

• Speed n = 6250r/min ± 25r/min
• Torque P = 56.45N (5.76kgf)
• Power Nₑ = 6.6kW (9.0PS)
• Fuel consumption rate gₑ = 496g/kW·h ± 20g/kW·h (365g/PS·h ± 15g/PS·h)
• Gasket temperature tₛ = 170—175℃

Pre-ignition test (procedure 3) debugging parameters (10.4):

• Speed n = 5000r/min ± 20r/min
• Torque P = 44.1N (4.5kgf)
• Power Nₑ = 4.136kW (5.625PS)
• Fuel consumption rate gₑ = 448g/kW·h ± 20g/kW·h (330g/PS·h ± 15g/PS·h)
• Gasket temperature tₛ = 170—175℃

Laboratory ambient temperature: 23—27℃ (8.2, 9.2, 10.2).

7. Sampling and sample preparation

• 6.1 Each evaluation requires sample oil 25L.
• 8.1 The high reference oil, sample oil, and low reference oil used in the test are all mixed with fuel oil according to 1:20(V/V). High reference oil preparation 8L, test oil preparation 6L, low reference oil preparation 3L.
• 9.1 The sample oil is mixed with fuel oil according to 1:20(V/V); one test requires approximately 225L of mixed oil.
• 10.1 The sample oil is mixed with fuel oil according to 1:20(V/V); one test requires approximately 200L of mixed oil.

8. Analysis procedure

7 Preparation of engine, dynamometer equipment, and measuring instruments

• 7.1 Break-in specification for the evaluation test engine: a new engine or an engine with replaced piston and cylinder block must undergo break-in; the break-in specification shall be carried out according to the provisions of Appendix J. The break-in oil is B-203 mixed with fuel oil according to 1:20(V/V).
• 7.2 Cleaning of the engine
  • 7.2.1 After break-in, disassemble the engine; the piston and piston rings, and the cylinder head are heated and boiled in cleaning fluid for 2—3h, and carbon deposits on the piston top, inner cavity, and piston ring grooves are removed. Be careful not to scratch the surfaces with sharp tools; clean with solvent oil before assembly.
  • 7.2.2 The inner surfaces of the exhaust pipe and muffler must be cleaned thoroughly; carbon deposits are not allowed to remain in the small ventilation holes in the muffler.
  • 7.2.3 The exhaust port of the cylinder block and the inner surface of the cylinder liner are washed clean with solvent oil; for the carburetor, focus on cleaning the main metering orifice, main nozzle, and idle metering orifice.
• 7.3 Engine assembly conditions: before assembly, the piston and cylinder liner, piston rings and ring grooves, spark plug gap, carburetor metering orifice dimensions, etc., are required to be selected and measured according to the dimensions specified in the assembly conditions of Appendix E.
• 7.4 Assembly of the engine: assemble the engine with the cleaned parts according to the assembly conditions of clause 7.3.
  • 7.4.1 The piston ring positioning pin and the piston ring opening must be aligned. The arrow direction marked on the piston top must be aligned with the exhaust port.
  • 7.4.2 Install the connecting rod small end needle roller bearing, drive in the piston pin, install the retaining ring; before assembly, apply a little high reference oil to the needle roller bearing and piston pin.
  • 7.4.3 When assembling the cylinder block, apply a little high reference oil to the inner surface of the cylinder liner, install the cylinder copper gasket, and apply high reference oil.
  • 7.4.4 After installing the cylinder head, tighten the nuts in a cross sequence, tightening torque 25N·m.
  • 7.4.5 Spark plug tightening torque 20N·m.
• 7.5 Dynamometer equipment and measuring instruments must be calibrated annually and before arbitration tests. Before each test, systematically check whether the dynamometer equipment and instruments are normal.

8 High-temperature lubricity test

• 8.2 The laboratory ambient temperature is required to be between 23—27℃, and the test should be completed continuously.
• 8.3 Lubricity test procedure
  • 8.3.1 Debug engine parameters (see Section 6).
  • 8.3.2 Test procedure: throttle fully open, n = 5000r/min ± 25r/min, tₛ = 170℃ ± 1℃. After stable operation under the above conditions for 40min, adjust the cooling air so that tₛ = 178—180℃; after stable operation for 3—5min, quickly turn off the cooling air, move away the air outlet to avoid interference from external wind sources in the air duct and other possible external cooling air.
  • 8.3.3 Collect torque drop data: the microcomputer in the ready state collects the torque drop value and corresponding time value as the spark plug gasket temperature rises from 190℃ to 290℃, collecting gasket temperature, torque, speed, and time every 10℃ interval.
  • 8.3.4 Restore cooling air: when tₛ reaches 290℃ and the microcomputer has collected the torque at this point, restore the operation of the cooling fan, and at the same time restore the air outlet to its original position, reduce the throttle to half of that during the test, keep the engine speed at 5000r/min, and make tₛ return below 170℃.
  • 8.3.5 Repeat the above operation of 8.3.2—8.3.4; repeat the test with high reference oil 4 times, and collect the corresponding four sets of gasket temperature, torque, speed, and time values.
  • 8.3.6 Oil change operation: after the high reference oil has undergone 4 lubricity tests, control the engine throttle at the idle position, pull off the carburetor fuel inlet pipe, burn off the residual fuel in the carburetor until the engine stops by itself, drain the fuel in the pipeline from the fuel tank to the carburetor, then insert the inlet pipe into another prepared mixed oil tank, restart the engine, and under the operating conditions listed in 8.3.2, run the engine for 30min.
  • 8.3.7 Test sequence: according to the operating procedure of 8.3.2—8.3.5, carry out the high-temperature lubricity tests of the four groups of oil samples listed in Table 2 in sequence, and collect the parameters listed in Table 2.

Table 2 Lubricity test sequence and representative symbols for each parameter

9 Deposit test

• 9.3 Before assembling an engine that meets the deposit test assembly conditions, weigh the piston and exhaust elbow, accurate to 1mg and 1g respectively, in order to calculate the weight of deposits after the test.
• 9.4 Test procedure
  • 9.4.1 Debug engine parameters (see Section 6).
  • 9.4.2 Break-in operation: after the engine reaches the 9.4.1 adjustment conditions, perform the 3h break-in operation according to Table 3.

Table 3 3h Break-in operating conditions

• 9.4.3 Power measurement at 8 speed points before the test: after the 3h break-in operation, replace the spark plug and air filter element, and with the throttle fully open perform power measurement at 8 speed points from high speed 7500r/min to low speed. The speeds are respectively 7500, 7000, 6500, 6000, 5500, 5000, 4500, 4000r/min. Record (may be collected by computer) speed, torque, power, fuel consumption, gasket temperature, exhaust temperature, atmospheric pressure and ambient temperature. At 7500r/min, the gasket temperature tₛ is controlled to 170—175℃; at other points the air flow may not be adjusted. Operate stably at each point for 3—5min, measure fuel consumption twice, and calculate the arithmetic mean of the power at 8 points F₁.
• 9.4.4 Deposit test procedure: Table 4 shows the deposit test operating conditions for one cycle of the engine 2h.

Table 4 Deposit test operating conditions

Note: 1) the 50hth does not perform the 10min idle operation. Record during the test: speed, torque, power, fuel consumption, gasket temperature, exhaust temperature, atmospheric pressure and room temperature.

• 9.4.5 Power measurement at 8 speed points after the test: replace the spark plug and air filter paper element. According to the provisions of 9.4.3, measure the power values at 8 speed points, record other operating parameters, and calculate the arithmetic mean of the power at 8 points F₂.
• 9.4.6 Conduct cleanliness rating: the time interval between completion of the test and disassembly of the engine shall not exceed 2h, and the time interval between removal of the piston and the cleanliness rating shall not exceed 8h. Before removing the piston pin, first evaluate the freedom of the piston rings and score the freedom; after removing the piston rings, rinse off the floating oil on the piston with solvent naphtha or standard fuel oil, then weigh with a balance accurate to one ten-thousandth of a gram to obtain the net weight of carbon deposits on the piston (g). Inspect the following items: whether the cylinder is scratched; the condition of carbon blockage in the exhaust pipe; the condition of carbon deposits on the spark plug. Before the piston cleanliness rating, take color photographs of obvious carbon deposit locations such as the piston, cylinder head, cylinder block exhaust port and exhaust pipe port, and muffler core. The cleanliness rating uses a merit score, see Appendix F for details.
• 9.4.7 Boil and wash the piston, piston rings, cylinder head and exhaust pipe with cleaning liquid; do not use sharp tools to clean carbon deposits on the piston and cylinder head.
• 9.4.8 Install, assemble and adjust the engine according to the provisions of 7.4. Perform the 3h break-in operation according to the provisions of 9.4.2. Perform power measurement at 8 speed points according to the provisions of 9.4.3, and calculate the arithmetic mean of the power at 8 points F₃.
• 9.6 Calibration test: if the apparatus has not been used for one year or after ten deposit tests, before formal evaluation a deposit test must be carried out with standard reference oil according to this operating procedure. When using B-201 standard reference oil, operate according to the deposit test conditions for 50h; the deposit effect coefficient Ed should be greater than 0.86, the cleanliness merit score should be greater than 100 points, and the exhaust blockage rate should be less than 13.2%.

10 Pre-ignition test

• 10.3 Prepare an engine that meets the conditions for the pre-ignition test.
• 10.4 Adjust engine parameters (see Section 6). Replace with a new spark plug and air filter paper element.
• 10.5 Pre-ignition test operating conditions: the test is carried out continuously in 3 stages, with operating conditions as in Table 5. Total test time 51h 30min.

Table 5 Pre-ignition test operating conditions (The content of Table 5 in the original text is source-text extraction missing, requires confirmation against the source standard (source-text extraction))

During the entire test process, continuously record the spark plug gasket temperature and torque. When the gasket temperature suddenly rises by less than 10℃, the recorder displays an alarm; at this time the torque suddenly drops, indicating a small pre-ignition. When the gasket temperature suddenly rises by more than 10℃, the alarm system automatically shuts down, indicating a large pre-ignition; record the test time T at which the pre-ignition occurs. If T is less than 45h, it indicates the sample oil is unqualified and the test should be terminated. If T is greater than 45h, execute the procedures of clause 10.6 and clause 10.7.

• 10.6 Inspect the engine: disassemble the piston, check whether the piston and cylinder are scratched or scored; if there is cylinder scoring or hot ring sticking, stop the test. If the above conditions are caused by lubricating oil quality problems, the oil sample is considered unqualified. If caused by unqualified engine assembly, the test must be redone. Inspect and record whether the spark plug has carbon deposits, whiskers or bridging; replace the spark plug if contamination is severe.
• 10.7 Reassemble the engine: reassemble the engine and continue the original procedure test. If a second large pre-ignition occurs, record the time of the large pre-ignition and terminate the pre-ignition test. If no second large pre-ignition occurs, continue the test until the end of the test.
• 10.9 Calibration test: if the apparatus has not been used for one year or after ten pre-ignition tests, before formal evaluation a pre-ignition test must be carried out with standard reference oil according to this operating procedure; during the test one large pre-ignition must occur, and the time at which the large pre-ignition occurs must be greater than 45h; if no large pre-ignition occurs or more than one large pre-ignition occurs, the engine must be adjusted and the calibration test redone.

Appendix E Test engine assembly conditions

Table E1

Appendix F Engine cleanliness rating method

• F1 Piston ring freedom rating
  • F1.1 Free ring: score is 10 points.
  • F1.2 Blunt ring: score is 9.5 points.
  • F1.3 Blunt ring and cold-stuck ring rating table

Table F1

• F1.4 Hot-stuck ring rating table

Table F2

• F2 Rating of carbon deposits and varnish in piston ring grooves: remove the piston rings from the piston, rinse off the floating oil on the piston with solvent naphtha, but do not rinse off the deposits on the piston.

Table F3

The demerit score for ring groove deposits is calculated as follows: S is the percentage of the ring groove bottom area covered by a certain color of deposit multiplied by the color coefficient. The total demerit score for that ring groove = ΣS (sum of demerit scores for each color). The deposit merit score for that ring groove = 10-ΣS.

• F3 Piston ring land deposit rating: refers to the rating of the shoulder portions between the ring grooves.
• F4 Piston inner cavity surface deposit rating
  • F4.1 Piston inner cavity top deposit rating.
  • F4.2 Piston inner cavity skirt surface deposit rating: refers to the rating of the portion below the piston pin centerline in the inner cavity.
• F5 Rating of carbon deposits and varnish on the outer surface of the piston skirt: refers to the rating of the piston outer surface portion below the piston ring grooves.
• F6 Cylinder head surface deposit rating: refers to the deposit rating of the cylinder head combustion chamber surface portion.
• The deposit ratings for each part F4, F5, F6 are all the same as the ring groove rating method.
• F7 Ring land scratch rating table

Table F4

• F8 Scoring table: if cylinder seizure or scoring occurs due to oil quality, the evaluation test is declared failed. If scoring occurs due to oil quality, scoring is required.

Table F5

Appendix J Engine break-in specification Total running-in time is 12.5h in total.

Table J1

(Note: Some cells in Table J1 have severe source-text extraction noise, and the specific correspondence requires confirmation against the source standard (source-text extraction))

9. Qualitative and Quantitative and Calculation Formulas

8.4 Test Results and Acceptance Criteria

• 8.4.1 Data Processing

Discrimination index Dᵢ = (ΔMOT torque / ΔMOT time) / (ΔMOH torque / ΔMOH time) ······ (1)

Where Dᵢ is the discrimination index, used to evaluate lubricating oil quality.

Selectivity index Sᵢ = [(ΔMOL torque / ΔMOL time) / (ΔMOH torque / ΔMOH time)] × 100 ······ (2)

Where Sᵢ is the selectivity index, used to control the test and check the reliability of the engine in distinguishing high and low reference oils.

• 8.4.2 Lubricity Test Acceptance Criteria
  • Dᵢ ≥ 1 indicates that the sample oil passes the lubricity test procedure.
  • Sᵢ ≤ -5% indicates that the evaluation procedure itself has reliable test data.
  • For high reference oil (B201) and low reference oil (B203), in the L-ERB lubricity test, the value of Sᵢ shall be ≤ -5%. If the selectivity index is too high, the engine needs to be readjusted and the lubricity test redone.

9.5 Deposit Test Results and Acceptance Criteria The arithmetic mean power values F₁, F₂, F₃ at the measured 8 speed points shall be corrected for atmospheric pressure and ambient temperature. The correction formula is detailed in Appendix G. Using F₁, F₂ and F₃ corrected for atmospheric pressure and ambient temperature, calculate the deposit effect coefficient Ed. Deposit effect coefficient Ed = (F₁ - F₂) / (F₁ - F₃) (The original formula source-text extraction is unclear, requires confirmation against the source standard (source-text extraction)) Acceptance criteria: The deposit effect coefficient Ed of the sample oil shall be greater than or equal to the deposit effect coefficient of the standard reference oil. The cleanliness merit rating is greater than the cleanliness rating of the low reference oil, and the exhaust port blockage is not greater than the exhaust port blockage percentage of the low reference oil.

10.8 Pre-ignition Test Results and Acceptance Criteria

• The number of major pre-ignitions occurring with the sample oil during the test shall not be more than that of the standard reference oil.
• The time to the first major pre-ignition shall be greater than or equal to the time to major pre-ignition of the standard reference oil.
• When using B201 standard reference oil for engine calibration, the time to major pre-ignition of the sample oil shall be greater than or equal to 45h.

Appendix G Engine Power Correction Formula for Different Atmospheric Pressures and Ambient Temperatures During the test, the atmospheric pressure is P₀, and the ambient temperature is t₈. The standard state specified by China's motorcycle industry is: atmospheric pressure 1000hPa (equivalent to 750mmHg), ambient temperature 25℃. When checking engine power, the corrected power is allowed as the basis. Power correction is calculated according to formula (G1):

F_c = F' × (1000/P₀) × √[(t₈ + 273) / (25 + 273)] ······ (G1)

Where: F'—measured power value; F_c— corrected power value. (Note: Formula source-text extraction contains noise, the specific form requires confirmation against the source standard (source-text extraction))

10. Precision

Not provided in the available source.

11. Report

Not provided in the available source (Table 6— and Table 10 are test data record tables, with severe source-text extraction missing, requires confirmation against the source standard (source-text extraction)).

12. Normative References

• GB/T 255 Petroleum products — Determination of distillation characteristics
• GB/T 257 Engine fuels — Determination of saturated vapor pressure (Reid method)
• GB/T 259 Petroleum products — Test method for water-soluble acids and alkalis
• GB/T 378 Engine fuels — Copper strip corrosion test method
• GB 1883 Reciprocating internal combustion engines — Terminology
• GB/T 1884 Petroleum and liquid products — Determination of density
• GB 1922 Solvent naphtha
• GB 5360 General technical specifications for motorcycle gasoline engines
• GB 5363 Bench test methods for motorcycle gasoline engines
• GB/T 5487 Determination of gasoline octane number