ASTM D6593 test method for evaluation of automotive engine oils
ASTM D6593 standard test method for Evaluation of Automotive Engine Oils for Inhibition of Deposit Formation in a Spark-Ignition Internal Combustion Engine Fueled with Gasoline and Operated Under Low-Temperature, Light-Duty Conditions
12. Test Procedure
12.1 Pre-test Procedure:
12.1.1 Engine Break-In Procedure - Run break-in schedule listed in Table 6. Conduct the break-in before each test using the test oil.

12.1.1.1 Charge the engine with 3000 g of test oil before the break-in run. Run the engine at 1500 more or less 25 r/min and 37.6 kPa MAP until the oil temperature reaches 80 more or less 2°C or for at least 2 min. Record the dipstick level 20 more or less 2 min after shutdown. This shall be the Test Full mark for this test. Use the table in Annex A8 to determine the oil level.

12.1.1.2 The laboratory ambient atmosphere shall be reasonably free of contaminants. The temperature and humidity levels of the operating area are not specified. Divert air from fans or ventilation systems away from the test engine.

12.1.1.3 The break-in allows an opportunity to check EEC system operation, blowby levels, air/fuel ratio for Stage II and III, check for leaks in the various systems and purge air from the cooling systems. Specifications concerning the break-in procedure are shown in Table 6. The engine start-up and shutdown procedures are detailed in 12.2.1 and 12.2.2 respectively.

12.1.1.4 During Step 1, bleed the air from the engine and RAC coolant systems and check all fluid systems for leaks.

12.1.1.5 During Step 2, check blowby level for the Stage II conditions. A high or low blowby flow rate at this time could be indicative of the blowby flow rate during the test. A ring gap adjustment can be performed at this time or after the break-in, but before the start of cycle 1, to achieve an adequate blowby flow rate. Testing has shown that a blowby range of 65 to 75 L/min during the break-in typically produces acceptable blowby during the test. However, it is the laboratory's discretion as to the need for a ring gap adjustment, noting that an adjustment cannot be made at any other time during the test.

12.1.1.6 During Step 3 (see Table 6) check Stage III air/fuel ratio, the operation of the idle load control system and EEC system operation. Allow the oil and coolant temperatures to reach 45 more or less 0.5°C. Exhaust gas analysis shall indicate 8.5 more or less 1.5 % CO and 3.0 % O2 max for both banks. If the exhaust gas analysis is not within the specified limits, check the idle load circuit and the EEC system operation with STAR tester.

12.1.1.7 Record all normal parameters in Steps 2 and 3 after operation at each step for 35 min. (Warning - Prolonged operation at a rich air-fuel ratio can cause excessive fuel dilution and alter test severity.)

NOTE 6 - The engine normally requires approximately 20 min to reach steady-state conditions after a step change.

12.1.1.8 Check and record oil level after break-in. If piston rings are regapped or replaced during or after the break-in, ensure that the oil level is brought back to the Test Full mark by adding new oil or removing oil.

12.2 Engine Operating Procedure:
12.2.1 Engine Start-up - Use the following detailed procedure each time the engine is started.

12.2.1.1 Turn on the ignition, safety circuits, fuel management system, fuel pump, and the rocker arm cover coolant pump.

12.2.1.2 Connect the intake-air supply duct.

12.2.1.3 Crank The Engine - The engine should start within 4 s. Since the engine has a crankshaft driven oil pump, cranking oil pressure may be low. If used, a low oil pressure ignition shutoff should be disabled during engine starting to allow the engine to start even though the oil pressure is low. The inclusion of this type switch could lead to excessive cranking time to start the engine.

12.2.1.4 If starting difficulties are encountered, the laboratory should not continue to crank the engine excessively. Perform diagnostics to determine the reason the engine will not start (ignition problems, insufficient or excess fuel, and so forth). (Warning - Excessive cranking times can promote additional fuel dilution of the test oil and can adversely affect the test.) (Warning - In addition to other precautions, do not attempt to pour gasoline into the intake-air horn.)

12.2.2 Engine Shutdown:
12.2.2.1 Scheduled Shutdown Procedure - Follow the procedure detailed as follows, each time a scheduled shutdown is performed. Scheduled shutdowns include shutdowns that occur during engine break-in and oil leveling:
(1) Bring the engine speed to 700 more or less 50 r/min for 10 min.
(2) Switch the ignition off. (Turn off power to the EEC and ignition, maintain power to the keep alive memory (KAM).)
(3) Turn off fuel pump
(4) Reduce the intake-air pressure to atmospheric.

12.2.2.2 Unscheduled Engine Shutdown - Follow the procedure detailed as follows, each time an unscheduled engine shutdown is performed:
(1) Stop test timer when ramp down starts.
(2) Ramp to Stage 3:

From Stage 1 - 15 s speed and load setpoint ramp; 6 min setpoint ramp of other controlled parameters.

From Stage 2 - Perform Stage 2 to 3 ramp (Table 4).

NOTE 7 - Total cooldown time is 6 min after the initiation of the ramp to Stage 3 conditions.

(3) Switch the ignition and RAC coolant pump off (turn off power to the EEC and ignition, maintain power to the KAM).
(4) Turn off fuel pump.
(5) Reduce the intake-air pressure to atmospheric.

12.2.2.3 Start-Up After Unscheduled Shutdown - Follow the procedure detailed as follows, each time an engine start-up is performed after an unscheduled shutdown.
(1) Start - 5 min in Stage 3, then to:
Return to Stage 1 - Stage 3 to 1 ramp (Table 4).
Return to Stage 2 - 60 s speed and load setpoint ramp; 10 min setpoint ramp of other controlled parameters.

NOTE 8 - Test time resumes after all controlled parameters are within specification

12.2.2.4 Start-Up After Oil Leveling Period - Follow the procedure detailed as follows, each time an engine start-up is performed after an oil leveling period.
(1) Start - 5 min in Stage 3; then Stage 3 to 1 ramp (Table 4).

12.2.3 Cyclic Schedule, General Description:
12.2.3.1 The test is composed of three stages as shown in Table 2. Together, the three stages comprise one cycle. Each cycle lasts 4 h and is repeated 54 times for a total of 216 h. Six consecutive cycles are completed each 24-h period. Every sixth cycle is modified to provide time for oil sampling and leveling. This modification is described in 12.3.1.

12.2.3.2 Ramping requirements specifying parameter change rates are shown in Table 4. The rate of speed, temperature, and load changes, as well as the amount of enrichment between stages, can influence sludge severity and engine component wear. Therefore, ramping rates are very important.

12.2.4 Unscheduled Downtime - The 30-min oil leveling periods are the only scheduled shutdowns allowed during the test and are counted as test time. However, the test can be interrupted to perform necessary maintenance (see 12.3.5). Note all unscheduled downtime on the Supplemental Operational Data Form of the final test report.

12.2.5 Resumption of Test Time After Unscheduled Shutdown - After an unscheduled shutdown, test time does not begin until the engine has reached operating conditions for the stage at which the shutdown occurred.

12.3 Periodic Measurements and Functions:
12.3.1 Blowby Flow Rate Measurement - Every sixth cycle, measure and record the blowby flow rate at 30 more or less 5 min into Stage II. The engine shall be stable and operating at normal Stage II operating conditions. Measure blowby when the gas temperature is at least 32°C. Blowby gas temperature shall not differ from the laboratory average by more than more or less 5°C. The installation of the blowby flow rate measurement apparatus is shown in Fig. 7. The procedure for measuring blowby flow rate is detailed in 12.3.1.1. Complete only one set (Stage II) of blowby flow rate measurement during each six cycles. Under special circumstances additional blowby flow rate measurements can be performed to determine or verify a problem with the flow rate measurement apparatus or the engine. Record additional blowby flow rate measurements and an explanation of the reason for the additional measurements. Include these data in the supplemental operational data in the final test report.

12.3.1.1 Measurement Procedure:
(1) Connect the apparatus pressure sensor to the dipstick tube.
(2) Open the bleeder valve completely.
(3) Connect the bleeder line to the three-way valve.
(4) Position the three-way valve to divert intake manifold vacuum from the engine PCV valve to the dummy PCV valve in the blowby measurement apparatus.
(5) Connect the hose from the blowby meter surge chamber to the 15.9-mm (5/8-in.) inside-diameter air vent hose on the air cleaner.
(6) Adjust the bleeder valve to maintain crankcase pressure at 0 more or less 25 Pa.
(7) Record the differential pressure, blowby gas temperature, and the barometric pressure.
(8) Disconnect the apparatus pressure sensor and reconnect the engine crankcase pressure sensor to the dipstick tube.
(9) Disconnect the surge chamber hose from the air vent hose.
(10) Position the three-way valve to divert intake manifold vacuum to the engine PCV valve and disconnect the bleeder line from the three-way valve.
(11) Connect the air vent hose to the intake-air cleaner.
(12) Calculate the blowby flow rate and correct the value to 38°C and 100 kPa using the calibration data for the orifice.
corrected blowby flowrate = blowby flowrate
x (3.100(P/273.15+T))(0.5)
where:
P = baro-pressure, kPa, and
T = gas temperature,° C.

12.3.2 Ignition Timing Measurement - Ignition timing is set by the EEC and can only be checked with a STAR tester. Ignition timing need only be checked if improper EEC and ignition operation is suspected.

12.3.3 Exhaust Gas Analysis:
12.3.3.1 The recorded readings for exhaust gas Lambda are taken during each stage and each cycle and shall be measured immediately after the engine oil and coolant temperatures have reached steady-state conditions (approximately 20 more or less 5 min into each stage). The data are used to confirm that the EEC system is operating the engine at the correct air/fuel ratio.

12.3.4 Oil Additions and Used Oil Sampling:
12.3.4.1 Oil Leveling and Sampling Procedure - Make up oil additions for leveling and oil sampling occur at 24-h intervals. Annex A10 shows the cycle when this is to occur. Used oil additions are permitted only during engine reassembly for maintenance (see 12.4.2.2). Add new oil to the engine only when the level is more than 400 g below the original test full level. Add only enough new oil to reach the 400-g low mark. No other new oil additions are permitted during the test, except after piston ring gap adjustment (see 12.1.1.8). In the event that the oil level is above the test full mark, do not remove oil until the level is greater than 200 g above the test full mark. Drain off a sufficient amount of oil so that the level is at the 200 g above test full mark. Record the amount drained on the oil leveling sheet. The procedure is shown on the Oil Sampling, Addition and Leveling Worksheet in Annex A10. This form serves as the oil sampling and oil addition data sheet.
(1) Remove a 150-mL purge sample within first 10 min of Stage III.
(2) Remove a 60-mL analysis sample within first 10 min of Stage III.
(3) Return the purge sample to the engine.
(4) Shut-down the engine 10 min after the start of Stage III. Do not shut off the RAC coolant pump.
(5) Record the dipstick level in mm 20 more or less 2 min after the engine is shutdown.
(6) Compute the oil level in grams. The difference between the oil level and the Test Full mark is oil consumed or gained. Use the chart in Annex A8 to determine the level. Do not add oil at 216 h. This allows the final drain to be used as a backup to the 216 h sample.
(7) If the level is more than 400 g below the Test Full mark, record the amount of new oil added to bring the level to the - 400 g mark. However, never add more than 400 g during an oil addition.
(8) If the level is more than 200 g above the Test Full mark, record the amount of oil drained to bring the level to the +200 g mark.
(9) Restart the engine 30 more or less 1 min after shutdown (Step 4). Allow the engine to run at Stage III conditions for 5 more or less 1 min, then resume normal operation.

12.3.5 General Maintenance - The 30-min scheduled shutdown periods during oil leveling allow limited opportunity for engine and stand maintenance. In addition, the test can be shut down at any convenient time to perform unscheduled maintenance. However, the duration of a shutdown should be minimized. Report any unscheduled shutdown on the Supplemental Operational Data Sheet.

12.4 Special Maintenance Procedures - Functions that require special maintenance procedures are listed in this section. These maintenance procedures are specifically detailed because of the effect on test validity or because they require special care while being completed.

12.4.1 Blowby Flow Rate Adjustment - A blowby adjustment may only be made during the break-in or within the first 48 h of the test. Blowby may drop from the break-in level but the corrected average Stage II blowby for the test during the first 120 h of the test shall fall within the range from 60 to 70 L/min. Adjust the blowby by changing the ring gaps or replacing piston rings as necessary. Ensure that the ring and piston combination in each cylinder meet the criteria in Table 1. Use the ring cutting procedure outlined in 7.8.5.2.

12.4.1.1 High Blowby Flow Rate Adjustment - Reduce high blowby flow rate by replacing the compression rings with new rings that have smaller ring gaps.

12.4.1.2 Low Blowby Flow Rate Adjustment - Increase low blowby flow rate by increasing the ring gaps of the compression rings.

12.4.2 Engine Disassembly and Reassembly for Maintenance (Before End of Test):
12.4.2.1 Engine assembly and disassembly shall adhere to the procedures in 7.8 and 12.6.2, respectively

12.4.2.2 When the engine is disassembled for maintenance, drain as much test oil as possible from the oil pan, and retain the oil for installation in the engine after reassembly. Take precautions to ensure the oil is not contaminated and to ensure the deposits are not disturbed on any parts that are used to determine the final test results. The Ford 4.6L engine contains numerous areas that hold oil after the engine is drained. All parts should be placed in or over clean drain pans to collect oil that drains off while maintenance is being performed.

12.4.2.3 During reassembly, used, drained test oil may be used to lubricate the engine parts. Do not use EF-411 oil or new test oil during engine reassembly. After the engine has been reassembled, charge the oil pan with the oil removed from the oil pan and collected from the engine parts during disassembly and maintenance. Record all new oil additions and report them in the Supplemental Operational Data.

12.5 Diagnostic Data Review - This section outlines significant characteristics of specific engine operating parameters. The parameters can directly influence the test or may be used to indicate normalcy of other parameters.

12.5.1 Manifold Absolute Pressure - Manifold absolute pressure is used in Stages I and II to control engine throttle position.

12.5.2 Engine Load - Engine load is not controlled in Stages I and II. It should remain relatively constant throughout a test and from test to test. Large differences in load reading could be indicative of control or engine problems.

12.5.3 Fuel Consumption Rate - The fuel consumption rate should remain relatively constant throughout the test. Fuel consumption rate is not a specifically controlled parameter but is used as a diagnostics tool.

12.5.4 Spark Knock - Spark knock does not normally occur in the VG test. The octane rating of the fuel, ignition timing, engine speed and load, and operating temperatures do not promote spark knock. Spark knock indicates abnormal combustion is occurring and can cause extensive engine damage. Take corrective action immediately if spark knock is noted. Errors in the measurement and control of engine load, ignition timing, operating temperatures, and air/fuel ratio may result in spark knock.

12.5.5 Exhaust Gas Component Levels:
12.5.5.1 Use the Lambda levels in the exhaust gas to determine the characteristics of combustion that occur during the test. Use this parameter to determine the normalcy of combustion and any significant changes in combustion that occur throughout a particular test. Lambda in all three stages is controlled by the program in the EPROM chip. No adjustments can be made to change the exhaust gas Lambda. If Lambda differs from what appears in Table 2, check the EEC system. Correcting a fault in the EEC system is the only way to achieve the correct Lambda value.

12.5.6 Crankcase Pressure - Crankcase pressure is a function of blowby flow rate and PCV valve flow. High crankcase pressure is usually caused by high blowby flow rate or a significant loss of PCV valve flow. Incorrect three-way valve plumbing or port plugging also promotes high crankcase pressure. Low or negative crankcase pressure may be caused by low blowby flow rate or a restriction of vent air to the PCV valve.

12.5.7 Oil Pressure - The oil pressure is a function of oil viscosity and operating temperature. The oil pressure should remain consistent throughout the test, unless the oil exhibits a significant change in viscosity.

12.5.8 Oil Temperature Differential - The oil temperature differential is primarily a function of oil flow rate and oil viscosity and is normally stable throughout the test. The differential can change if the oil viscosity changes significantly during the test.

12.5.9 Coolant Temperature Differential - The coolant temperature differential is primarily a function of the coolant flow rate and is normally stable throughout the test. Large variations in the differential can be caused by coolant flow rate or temperature measurement errors. Coolant flow rate measurement errors can be caused by foreign objects in or near the venturi flowmeter.

12.6 End of Test Procedure:
12.6.1 Final Drain - Drain the engine coolant and RAC coolant immediately after the completion of the last test cycle. Engine oil can be drained with the engine in or out of the engine stand. Allow the engine to stand for 6 to 12 h in the same attitude in which it was positioned on the test stand prior to drain. This allows the oil to drain completely into the oil pan. Drain the oil from the engine.

12.6.2 Engine Disassembly - During disassembly, use extreme care not to disturb engine deposits and to ensure the original location of the parts can be identified with respect to either the cylinder number, valve location, or both.

12.6.3 Parts Layout for Rating:
12.6.3.1 Arrange the following parts in the parts rating area in accordance with the layouts detailed in this section. After the parts have been arranged, allow the parts to drain for 4 to 8 h before rating. Do not attempt to accelerate or force the oil draining. Any fixtures can be used to support the parts as long as they orient the parts in the specified configurations.

12.6.3.2 Rocker Arm Covers - Position the RAC's vertically (upper jacket surface perpendicular to the ground) with the front of the RAC at the bottom.

12.6.3.3 Camshaft Baffles - Position the camshaft baffles vertically (top baffle surface perpendicular to the ground) with the rear of the camshaft baffle pointing down.

12.6.3.4 Cylinder Heads - Position the cylinder heads with RAC gasket surface pointing down.

12.6.3.5 Front Cover - Position the front cover in the same orientation as it is installed in the engine.

12.6.3.6 Oil Pan - Position the oil pan upside down, with the pan rail at a 45° angle, with sump end pointing down.

12.6.3.7 Oil Pan Baffles - Position the oil pan baffles vertically on the front edges.

12.6.3.8 Oil Screen and Pickup Tube - Position the oil screen and pickup tube in the same orientation as they are installed in the engine. The screen should be raised off of the supporting surface to allow drainage. A fixture is necessary to support the oil screen and pickup tube.