LOW-TEMPERATURE PUMPABILITY CHARACTERISTICS OF ENGINE OILS IN FULL-SCALE ENGINES Prepared by the Data Analysis Panel of ASTM Committee D-2 R&D Division Vll-C on Non-Newtonian, Low-Shear Phenomena ASTM DATA SERIES PUBLICATION 57 List Price $16.00 05-057000-12 # AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa 19103 ©by AMERICAN SOCIETY FOR TESTING AND MATERIALS 1975 Library of Congress Catalog Card Number: 75-24603 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Printed in Long Island City, N.Y September 1975 Data Series DS 57 American Society for Testing and Materials Related ASTM Publications Multicylinder Test Sequences for Evaluating Automotive Engine Oils, STP315F (1972), $8.25, 04-315060-12 Shear Stability of Multigrade Crankcase Oil—IP Fleet Tests, DS 49-S1 (1974), $4.00, 05-049001-12 Single Cylinder Engine Tests for Evaluating Performance of Crankcase Lubricants, STP 509 (1972), $5.00, 04-509000-12 Editorial Staff Jane B Wheeler, Managing Editor Helen M Hoersch, Associate Editor Charlotte E Wilson, Senior Assistant Editor Ellen J McGlinchey, Assistant Editor DS57-EB/Sep 1975 SUMMARY Low-temperature engine oil pumpability data have been obtained on thirteen ASTM Pumpability Reference Oils in seven full-scale test engines Borderline Pumping Temperatures based on gallery oil pressure traces were determined for all thirteen Reference Oils in four of the test engines, and for nine of the Reference Oils in all seven test engines Data were also obtained as to the type of flow failure occurring (air-binding or flowlimited) and on rocker arm oiling times The results indicate substantial differences in pumpability among both test oils and test engines Possible reasons for these differences are analyzed, and a model, based on engine oil pump inlet system dimensions, is proposed This model accounts for some of the differences found in engine severity and the type of flow failure which occurs The pumpability data reported should provide the basis for development of a laboratory bench test to predict engine oil pumpability Results from various bench tests and engine pumping rigs and their correlation with the full-scale engine data will be summarized in a later report INTRODUCTION AND BACKGROUND The current ASTM Committee D-2 Research and Development Division VII-C Task Force Program to evaluate the low-temperature pumpability properties of thirteen ASTM reference oils in seven full-scale test engines, five engine pumpability rigs, and a variety of bench tests was initiated at the request of SAE In 1970, a Task Group of SAE Fuels and Lubricants Subcommittee completed an inquiry to determine the extent of the low-temperature pumpability problem Based on the results of the survey, Subcommittee requested (1)* ASTM to "develop a simple laboratory test to measure the ability of an oil to flow to the engine oil pump inlet in a manner relatable to engine conditions, and to consider the relationship between low-temperature oil properties and the supply from the pump to critical engine parts." In response to the SAE request, ASTM Task Force members conducted exploratory tests in engines, engine pumping rigs, and laboratory bench rigs in an effort to obtain enough information to design a comprehensive cooperative program The ASTM Task Force concluded early in the program that they would have to obtain extensive full-scale engine data to serve as the basis for evaluating the ability of bench tests and engine pumping rigs to predict engine oil pumpability * Numbers in parentheses designate References at end of report Copyright © 1975 by ASTM International www.astm.org A literature search conducted early in 1970 revealed that no usable engine pumpability data existed In 1961, R G Moyer (2) conducted tests on an automotive oil pump rig His results showed that pumping failures occurred by air binding, and that an oil's pumpability in his rig could not be predicted by its 0°F (-17.8°C) viscosity, ASTM Pour Point, or channel point In 1963, T W Selby (3) evaluated the pumpability problem and concluded that existing shear rates in different parts of the engine and the viscosities of the Vl-improved oils at the existing shear rates determined where the oil failed to flow fast enough to satisfy the engine's demands The first-engine results were reported in 1971 by Smith and Graham (4), who showed that rocker arm oiling times could not be predicted by ASTM Pour Point, Brookfield viscosity, or Cold Cranking Simulator viscosity They found that some used oils were more pumpable than new oils and that engine design was an important factor in pumpability Boone, Crouse, and McLaughlin (5), however, found some indications that a tilt-can pour test could be used to predict an oil's rocker arm oiling time, but found no correlation between polymer type and low-temperature fluidity In 1972, Stewart and Spohn (6) motored an engine at 1650 rpm in a cold room at 0°F (-17.8°C) and -20°F (-28.9°C) using twelve commercial oils and nine laboratory blends to determine rocker arm oiling times and times to achieve normal gallery oil pressure They showed that oil temperature, oil pressure, engine speed, valve lifter type, flapper valve plate removal, and fuel dilution affected rocker arm oiling time, and that the time required to achieve normal gallery oil pressure was affected by oil temperature, oil screen removal, engine speed, and VI improver type They also found that neither the rocker arm oiling time nor the time to achieve normal gallery pressure could be predicted by Cold Cranking Simulator viscosity, Brookfield viscosity, tiltbottle pour time, or ASTM Pour Point Because of the confusion and lack of agreement which existed in 1972 concerning the scope and causes of the low-temperature pumpability problem, a joint ASTM-SAE Symposium was organized and held in May of 1973 to help reconcile the differences and to further define the problem Four papers (7-10) were presented in which engine studies, laboratory tests, and theoretical considerations were used to point out specific examples of lowtemperature pumpability problems and to identify several important variables Following the Symposium in 1973, the ASTM Low-Temperature Engine Oil Pumpability Task Force finalized their plans for a cooperative program and selected thirteen Pumpability Reference Oils (PRO's) These oils were supplied to all of the participants for their various evaluations The ASTM Task Force has completed the full-scale engine evaluations of the thirteen PRO's, but the bench tests and the engine pumping rig tests are not yet completed Therefore, this report summarizes only the fullscale engine data A follow-up report will summarize the bench test and engine pumping rig data and evaluate their ability to predict engine oil pumpability in full-scale engines Considerable test work by many different laboratories was required to obtain the data summarized in this report The laboratories which have participated in the various phases of the pumpability program are summarized in Appendix A, Table A-l The Data Analysis Panel members are also listed in this table PROGRAM ASTM Pumpability Reference Oils (PRO's) To ensure the availability of oils which could be used in engine tests and later in laboratory bench tests, a series of Pumpability Reference Oils was established The following criteria were used in formulating the Reference Oils: • Inclusion of commonly used types of viscosity index (VI) improvers commercially available in 1973 • Inclusion of Vl-improved oils which cover the widest SAE viscosity grade ranges commercially available • Inclusion of one set of oils containing the same VI improver, but different base stock wax levels • Inclusion of two oils containing no VI improver, and formulated so as to be Newtonian in the temperature range of interest • Inclusion of a commercial oil known to fail by air binding in a specific engine • Inclusion of one oil blended specifically to be soaktime sensitive • Inclusion of a standard additive package in all noncommercial oils formulated for this program (excluding the Newtonian oils) The thirteen PRO's along with their SAE viscosity grade, coded VI improver type, and base stock wax level are shown in Table New oil inspection data, including kinematic viscosities, Cold Cranking Simulator viscosities, Brookfield viscosities, and ASTM Pour Points are shown in Table Test Engines Six different engines were included in the program with a seventh engine, duplicating one of the six different engines, included to give an indication of test reproducibility The engines were selected on the basis of the number sold, the number of cylinders, rocker arm oiling method, and inlet system design characteristics A summary of these characteristics for each Table D-8 Flow-Limited BPT, °F Engine: PRO-01 03 05 06 07 08 09 10 11 12 13 15 16 oo Average(c) L-235 0-125 D-444 -22 -12 +1 -11 -12 -11 -23 -13 -10 -22 -12 (a) (d) (a) -6 (d) (d) (d) (a) -21 -17 -24 -26 +5 -7 -31 (d) (a) -6 (d) (d) (d) -25 -20 -15 -21 -24 -5 -34 (d) (a) -11 (d) (d) (d) (a) -22 -20 -25 -26 -10 -14.0 -17.8 +4 -5.2 -15.4 N-235-1 N-235-2 (a) -18 (a) -11 -19 -19 (a) (a) -24 -22 -28 -29 -12 -19.6 N-114 0-240 (a) -21 (a) -16 -21 -22 (a) (a) -28 -24 (a) -37 -17 (a) -28 -27 -27 -24 -25 (a) (a) -30 -30 (a) -37(b) -2Kb) -27.3 -9.6 -24.4 -29.0 -17.9 (a) Air-binding BPT (b) Estimated from partial data using average pressure-time slope from other oils (c) Averages for only those five oils that were flow limited in all seven engines (d) Not tested in this engine Average(c) — - -10.4 - -22.6 -19.7 - Table D-9 Air-Binding BPT, °F Engine(a): PRO-01 03 05 06 07 08 09 10 11 12 13 15 16 0-125 D-444 N-235-1 N-235-2 N-114 0-240 -32 (d) +10 (b) (d) (d) (d) -27 (b) (b) (b) (b) (b) (b) (d) -8 (b) (d) (d) (d) (b) (b) (b) (b) (b) (b) (b) (d) +10 (b) (d) (d) (d) -27 (b) (b) (b) (b) (b) -33 (b) +6 (b) (b) (b) -22 -28 (b) (b) (b) (b) (b) -37 (b) +9 (b) (b) (b) -17 -28 (b) (b) -30 (b) (b) -39 (b) (b) (b) (b) (b) -20(c) -27 (b) (b) -30 (b) (b) (a) No air binding was observed in Engine L-235 (b) Flow-limited BPT (c) Estimated from partial data using average pressure-time slope from other oils (d) Not tested in this engine 90 Appendix E SUPPLEMENTAL STATISTICAL ANALYSES Reference Oil BPT averages and engine BPT averages can be examined to determine which of these differ significantly Such a determination has been made on the nine oils run in all seven engines, and the analysis can be found in Appendix Table E-l Groupings of results encompassed by a 95 percent confidence interval will overlap in many cases Thus, while PRO-05 has a distinct value and PRO's 16 and 06 form a tight group, the other six PRO's form three overlapping groups In the case of engine BPT averages, while three overlapping groups can exist, the middle five engines (excluding L-235 and 0-240) appear to be a logical grouping While these groupings are readily determined from the data analysis, their relative importance is not felt to be very great since the standard error is probably inflated due to oil/engine interactions If the standard deviation term is large, the confidence interval is also large and obscures otherwise meaningful differences A similar analysis for the thirteen PRO's run in four engines is included in Table E-2 Oil/engine interactions also affect the precision and sharpness of these groupings 91 Table E-l Significant Groupings of Engine and Oil Averages - Basic 7x9 Program 95% Confidence Interval n = mean, n = observations, s = std dev Interval = n ± tv Vs^/n Oils = n ± t54 Vs2n - n ± 2.01 X 5.16/ VT" - n ± 3.92 Interval Width = X 3.92 = 7.84°F Engines Interval = n ± t^g s/V n = n ± 2.01 X 5.16/%^ = n ± 3.46 Interval Width = X 3.46 = 6.92°F Grouping PRO 05 16 06 12 11 13 10 15 01 Oils Avg BPT, °F +0.1 -9.6 -10.4 -19.7 -22.6 -25.6 -26.4 -27.3 -32.3 Code L-235 0-125 D-444 N-235-1 N-235-2 N-114 0-240 7.8°F Interval Width 92 Engines Avg BPT, °F -10.2 -16.3 -17.2 -18.3 -20.1 -23.1 -29.8 6.9°F Interval Width Table E-2 Significant Groupings of Engine and Oil Averages - Optional x 13 Program 95% Confidence Interval ri = mean, n = observations, s = std dev Oils Interval = n ± tv Vs^/n = n ± t39 5.46/ W = n ± 2.023 X 5.46/2 = n ± 5.52 Interval Width = X 5.52 = 11.04°F Engines Interval = n ± t48 5.46/ = n ± 2.01 X 5.46/3.6055 = n ± 3.04 Interval Width = X 3.04 = 6.08°F Grouping PRO 05 16 06 09 07 08 03 12 11 10 13 15 01 Oils Avg BPT, °F -2.8 -11.3 -12.5 -17.5 -18.8 -19.5 -19.8 -21.5 -23.8 -26.5 -27.5 -28.8 -32.8 Code 11.0°F Interval Width 93 Engines Avg BPT, °F L-235 -10.6 N-235-2 -19.9 N-114 -22.2 0-240 -28.1 6.1°F Interval Width Appendix F ROCKER ARM OILING TIMES 94 Table F-l Rocker Arm Oiling Times Engine L-235 PRO No Temp, °F 01 -11 -17 -21 -25 -31 -16 -21 -31 -36 -42 03 vo Ul _20** 05 -12 -13 -17 -22 -27 06 -6 -12 -22 RAO Time, Min Min Max Avg* 3.93 4.26 1.57 2.40 2.75 9.10 9.81 9.70 9.85 10.42 6.29 6.85 6.34 5.53 6.58 4.33 4.17 5.20 4.24 5.03 2.00 10.66 9.60 9.63 11.00 9.85 10.75 6.85 6.16 7.25 6.59 7.28 6.87 4.16 4.08 2.40 4.74 4.17 11.21 10.80 5.10 9.20 10.75 7.09 7.23 3.55 6.86 7.05 1.60 4.50 5.00 4.15 11.60 11.18 9.80 10.83 6.57 7.09 7.14 7.75 PRO No Temp, °F Min 07 -6 -12 -17 -22 08 Max Avg* 3.18 4.90 1.78 3.18 8.91 9.84 10.60 5.70 5.99 7.11 7.35 4.12 -11 -13 -17 -22 5.03 3.17 2.66 6.56 10.60 10.32 5.23 9.56 7.45 6.56 3.71 7.98 09 -8 -11 -15 3.42 4.27 3.00 9.52 11.82 14.75 6.58 6.82 7.70 10 -22 -24 -27 -31 -32** 2.15 4.13 3.52 3.27 6.65 10.33 10.48 10.80 5.80 10.28 -12 -15 -20 -21 -13** -16** 2.77 4.87 2.32 4.28 4.95 2.00 10.58 10.55 9.75 10.04 10.05 10.20 11 * Average of times for all rocker arms, ** Long soak (64 hr) RAO Time, Min PRO No Temp, °F 12 RAO Time, Min Min Max Avg* -6 -12 -15 -22 -27 -11** 3.55 2.16 2.66 5.00 2.75 2.46 9.95 9.83 10.67 10.08 11.78 8.65 6.59 6.25 7.65 7.42 7.76 6.65 13 -12 -16 -22 -28 -32 -37 3.98 2.53 1.93 3.93 5.50 5.68 10.60 9.14 9.53 10.78 11.48 9.72 6.56 6.53 7.04 6.85 7.90 7.67 6.57 6.61 6.80 4.13 7.91 15 -11 -13 -17 -23 -30 1.28 3.58 1.78 5.15 2.64 9.38 8.08 9.22 10.10 10.18 6.38 6.69 6.27 7.04 7.22 6.26 7.06 6.49 6.87 6.83 6.51 16 +7 +4 -12 2.10 5.17 3.94 5.67 8.47 9.17 9.66 10.76 6.35 6.92 6.54 7.54 Table F-2 Rocker Arm (Diling Times Engine 0-125 PRO No 01 Temp, °F -6 -23 -25 -28 -32 VO Q\ 05 06 10 11 +10 +10 +4 -5 -20 -25 -4 -11 -17 -24 Min RAO Time,* Min Avg Max 1.52 1.68 1.70 1.87 2.45 2.58 2.15 2.80 2.88 3.17 2.08 2.16 2.23 2.37 2.86 1.78 2.22 1.99 1.73 2.38 1.67 2.32 2.58 2.45 2.07 2.48 1.97 2.20 2.20 2.77 2.85 2.54 2.57 2.30 1.52 2.05 2.73 2.45 2.37 3.02 3.48 2.37 1.95 2.51 3.12 PRO No Temp, °F Min RAO Time,* Min Max Avg 12 -10 -19 2.22 1.85 2.93 3.52 2.59 2.49 13 -19 -25 -29 2.28 3.27 3.07 2.90 3.50 3.93 2.65 3.38 3.61 15 -9 -10 -15 -26 1.07 1.98 1.62 2.13 1.92 2.33 2.33 1.56 2.18 1.98 2.20** +5 -6 2.40 2.48 2.55 3.22 2.62 2.88 3.13 3.55 16 * Min = Oiling time for rocker arm No 12 Max = Oiling time for rocker arm No Avg = Average of oiling times for rocker arms No 1, 6, 12 ** Oiling time for No rocker arm not available RAO time for No used as best estimate of average -9 -10 - 2.51 2.72 2.83 3.40 Table F-3 Rocker Arm Oiling Times Engine D-444 PRO No 01 05 06 10 11 Temp, °F -29 -6 -7 -8 -9 -6 -26 -28 -29 -16 -20 -21 -24 -15** -17** RAO Time,* Min Min Max AV£ PRO No 2.1 1.6 12 1.6 1.8 1.7 6.4 2.8 2.8 3.2 2.9 2.3 2.9 3.8 4.0 2.1 2.8 1.2 1.4 1.4 3.6 2.0 13 1.1 0.8 0.9 1.1 0.8 1.1 2.5 2.8 1.9 1.6 2.0 3.3 3.8 0.8 1.7 2.7 3.0 2.4 2.0 2.4 3.6 3.9 1.5 2.3 15 16 * Rocker arms on left cylinder bank were observed Avg = Average of Min and Max RAO times observed ** Long soak (64 hr) Temp, °F -14 -16 -21 -20 -21 -22 -30 -15 -23 -25 -29 -3 -5 -10 RAO Time,* Min A Min Max vg 2.5 1.8 2.0 2.9 0.7 1.7 2.0 3.6 2.5 3.3 5.3 3.1 2.5 3.3 4.3 1.7 2.8 3.1 4.2 1.3 1.8 3.7 2.2 3.0 4.0 1.1 2.2 5.0 1.8 2.8 5.2 2.8 2.2 2.7 3.6 1.2 2.3 2.5 3.9 1.8 2.4 3.9 Table F-4 Rocker Arm Oiling Times Engine N-235 PRO No Temp, °F Mln RAO Time, Mln Max Avg* 01 -25 -29 -34 3.4 3.3 3.8 8.6 7.2 7.2 03 -15 -19 2.9 3.4 7.9 8.5 5.4 5.4 5.7 5.4 5.7 05 +10 +5 -11 1.7 0.7 2.6 6.4 7.6 8.0 4.1 4.9 5.9 V0 00 -15 -19 -21 06 07 -5 -10 -13 -15 2.7 3.3 2.4 3.4 1.5 4.3 1.1 -20 -22 2.6 3.4 08 -15 -20 09 -20 -22 8.2 7.7 9.3 9.3 9.2 9.8 6.7 5.6 5.2 6.1 5.5 5.3 6.0 5.0 8.5 7.2 5.8 5.7 4.3 4.6 8.1 8.2 5.7 5.9 3.1 2.0 7.9 13.0 5.6 6.7 * Average RAO time for all rocker arms ** Long soak (64 hr) PRO No 10 11 12 13 15 16 Temp, °F Min RAO Time, Min Max Avg* -25 -27 -28 -21 -22 3.2 3.1 1.9 2.2 1.9 7.2 8.7 6.9 7.6 8.3 5.2 5.0 4.9 4.5 5.2 -26 -20** -21** 3.7 4.0 4.7 11.3 8.6 9.2 6.2 6.2 6.7 -20 -24 9.2 -25 -27 -31 -26 -29 3.7 3.4 3.4 1.8 4.4 4.4 3.6 5.7 6.4 5.4 5.3 6.2 -11 -12 4.1 4.1 -15 4.6 10.0 7.4 7.3 8.1 7.1 8.0 8.6 8.0 8.5 5.7 6.0 6.0 6.0 6.4 Table F-5 Rocker Arm Oiling Times Engine 0-240 PRO No 01 vo vo Temp, °F -28 Min RAO Time,* Min Max Avg -30 -35 -37 4.50 4.55 4.75 4.92 6.10 6.28 6.63 6.58 5.54 5.63 5.87 5.98 03 -24 -28 -30 5.52 5.47 6.17 7.62 6.90 8.25 6.53 6.44 7.03 05 +5 +5 3.68 3.78 4.37 5.25 5.43 5.50 5.83 5.77 6.07 5.70 7.12 6.83 7.83 8.33 4.79 4.82 5.07 6.46 6.05 6.54 5.35 7.13 7.28 7.38 6.40 6.41 6.75 7.04 -7 -25 -27 -29 -30 06 07 08 -15 -20 -24 -27 -20 -20 -25 5.38 5.80 6.08 4.92 6.83 5.84 4.98 5.25 5.08 6.75 6.19 6.16 PRO No Temp, °F Min RAO Time,* Min Avg Max -22 5.63 8.10 7.10 -22 -28 4.40 4.98 6.52 6.75 5.36 6.11 11 -27 -27 -29 -32 -20** -25** 5.23 5.17 5.38 5.67 4.78 5.17 7.23 7.12 7.00 7.32 6.50 6.75 6.29 6.13 6.28 6.76 5.80 6.04 12 -20 -25 -28 -32 5.28 5.55 5.80 6.05 7.75 6.83 7.08 7.43 6.58 6.38 6.55 7.09 13 -20 -27 -30 4.77 5.10 5.57 7.07 7.18 7.75 6.08 6.36 6.89 -30*** 4.78 4.83 6.65 6.70 5.53 5.85 5.00 6.67 6.04 09 10 15 16 -32 -18 * RAO times were observed on right cylinder bank for rocker arms most remote from oil pump "Avg" is average RAO time for these rocker arms ** Long soak (64 hr) *** Data available for only rocker arms