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Covitch, Michael J.
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Extending SAE J300 to Viscosity Grades below SAE 20

SAE International Journal of Fuels and Lubricants

Chevron-David George
Imperial Oil Ltd-Chris May
  • Journal Article
  • 2010-01-2286
Published 2010-10-25 by SAE International in United States
The SAE Engine Oil Viscosity Classification (EOVC) Task Force has been gathering data in consideration of extending SAE J300 to include engine oils with high temperature, high shear rate (HTHS) viscosity below the current minimum of 2.6 mPa⋅s for the SAE 20 grade. The driving force for doing so is fuel economy, although it is widely recognized that hardware durability can suffer if HTHS viscosity is too low. Several Japanese OEMs have expressed interest in revising SAE J300 to allow official designation of an engine oil viscosity category with HTHS viscosity below 2.6 mPa⋅s to enable the development of ultra-low-friction engines in the future. This paper summarizes the work of the SAE EOVC Low Viscosity Grade Working Group comprising members from OEMs, oil companies, additive companies and instrument manufacturers to explore adoption of one or more new viscosity grades. Past studies relating HTHS viscosity to engine wear will be reviewed, and an analysis of the rheological properties of commercial SAE xW-20 oils will be presented. New data will also be offered to demonstrate the feasibility…
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Mechanical Degradation of Viscosity Modifiers in Heavy Duty Diesel Engine Lubricants in Field Service

ChevronTexaco-James A. McGeehan, Melvin Couch
The Lubrizol Corporation-Michael J. Covitch, Sherrie L. Wright, Barton J. Schober
Published 2003-10-27 by SAE International in United States
Modern multi-grade engine lubricants are formulated to “stay in grade” during field service. Viscosity loss during the early stages of lubricant life is commonly believed to be caused by mechanical degradation of the viscosity modifier in the engine [1]. The Kurt Orbahn shear stability bench test (ASTM D 6278, 30 cycles) has been the industry standard predictor of viscosity loss due to polymer shear in heavy duty diesel engine lubricants. However, the Engine Manufacturers' Association (EMA) has expressed some concern that it underestimates the degree of polymer shear found in certain engines in the field, such as the Navistar 6.0L HEUI (Hydraulic Electronic Unit Injector) Power Stroke engine; a more severe bench test would serve to improve correlation with this and other similar engine designs.This paper offers a new approach for critically examining the relationship between the bench test and field performance. Rather than indirectly measuring polymer shear via viscosity determination, a method for directly measuring olefin copolymer (OCP) molecular weight in heavy duty diesel drain oils was developed. The main advantage of this approach…
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Physical Processes Associated with Low Temperature Mineral Oil Rheology: Why the Gelation Index Is Not Necessarily a Relative Measure of Gelation

The Lubrizol Corp.-Richard M. Webber, Herman F. George, Michael J. Covitch
Published 2000-06-19 by SAE International in United States
The intent of industry and OEM factory fill oil specifications is to ensure lubricant pumping performance at low temperatures through rheological measurements using the Mini Rotary Viscometer and Scanning Brookfield tests. Often these tests provide conflicting information, yet lubricant formulations must be optimized to meet requirements of both tests. At the root of this issue is how test information is interpreted, since ultimately it is that interpretation that influences how specifications are set. In this paper, we focus on understanding the Scanning Brookfield test's gelation index which is part of ILSAC GF-2 and GF-3 specifications; our objective is to understand what is measured and its relation to meaningful low temperature lubricant performance.We approach this objective by measuring the low temperature rheology of mineral oils and lubricants formulated from these oils. Our focus is on describing the relation of the physical processes of wax crystallization to its effects on rheological properties. Three examples are provided to illustrate what the fundamentals of this work reveal about lubricant rheology. In the first two examples we investigate the effects…
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Topics in Lubricants

Charles Bovington, Michael J. Covitch, Philippe Duteurtre, Malcolm Fox, Alain Gauthier, Masakuni Hirata, Masabumi Masuko, John H. May, Yasuhiro Murakami, Harvey P. Nixon, Bengt Otterholm, Meinrad Signer, David Simner, Fumio Ueda
  • Special Publication (SP)
  • SP-1550
Published 2000-06-19 by SAE International in United States
The main themes of this book include: fuel economy formulating for performance rheology engine lubricant specifications additive effects on lubricant performance
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How Polymer Architecture Affects Permanent Viscosity Loss of Multigrade Lubricants

The Lubrizol Corporation-Michael J. Covitch
Published 1998-10-19 by SAE International in United States
Multigrade automotive lubricants contain polymeric viscosity modifiers which enable the oil to provide adequate hydrodynamic lubrication at high temperatures and good starting/pumping performance at low temperatures. Under operating conditions in engines, transmissions and gear boxes, polymeric additives undergo both temporary and permanent viscosity loss. The former is caused by flow orientation and the latter by molecular chain scission. Whatever the mechanism, original equipment manufacturers are interested in maintaining a minimum level of hydrodynamic viscosity from oil change to oil change. This is often expressed as a “stay-in-grade” requirement.Commercial viscosity modifiers (VM) span a wide range of chemistries and molecular architectures. An earlier paper (1)1 reported on the permanent viscosity loss characteristics of SAE 5W-30 engine oils differing in VM chemistry and speculated that differences in molecular structure - linear chains, A-B block copolymers and stars - could explain most experimental observations. This paper presents a similar study on a series of SAE 15W-40 heavy duty diesel engine oils formulated with OCP, styrene/butadiene, star and PMA viscosity modifiers. Very similar relative permanent viscosity losses to those…
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Recent Snapshots and Insights Into Lubricant Tribology

Michael J. Covitch, Jagadish Sorab, Simon C. Tung
  • Special Publication (SP)
  • SP-1116
Published 1995-10-01 by SAE International in United States
Durability-protected, low friction operation of lubricated engine component has become increasingly important in recent years due to diverse forces driven by technology, legislation, and competition. This publication reflects the depth of interest in engine lubrication issues. Contents include: studies on friction characteristics of reciprocating engines; investigation on oxidation stability of engine oils using laboratory scale simulator; wear mechanisms of valve seat and insert in heavy duty diesel engine; computer model of the degradation of VI improvers in engine service and bench tests; effects of aging on frictional properties of fuel efficient engine oils; simultaneous piston ring friction and oil film thickness measurements in a reciprocating test rig; review and evaluation of lubricated wear in simulated valve train contact conditions; mechanism studies with special boundary lubricant chemistry; and more.
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Engine Oils-Rheology and Tribology

Michael J. Covitch, Simon C. Tung
  • Special Publication (SP)
  • SP-1069
Published 1995-02-01 by SAE International in United States

This special publication covers the "hot" topics facing the lubricating industry including fuel economy, environmental friendliness and cold weather performance. Hardware durability has, is and will forever be a major concern as well.

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Rheotribology of Automotive Lubricants and Fluids

Simon C. Tung, Michael J. Covitch
  • Special Publication (SP)
  • SP-1055
Published 1994-10-01 by SAE International in United States
This publication presents a cross-section of information covering a broad perspective of lubricant performance based upon recent tribological and rheological research from around the globe. Partial contents include: assessment of the low-temperature incompatibility risk of commercial engine oils; evaluation of reversible and irreversible viscosity losses using the viscosity loss trapezoid; and the influence of lubricant rheology of friction in the piston ring pack;
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Tribological Insights and Performance Characteristics of Modern Engine Lubricants

Michael J. Covitch, Simon C. Tung
  • Special Publication (SP)
  • SP-0996
Published 1993-10-01 by SAE International in United States
This informative publication covers the most recent advances in lubricant tribology. Topics are organized by testing; friction and wear; rheology; and oil degration. Contents include: fuel efficiency screening tests for automotive engine oils; accurate element analysis of multigrade lubricating oils by ICP method: effect of viscosity modifiers; the possible role of surface tension in the reduction of top ring drag; surface and tribological characterization of coatings for friction and wear reduction; measurements of cylinder liner oil film thickness in a motored diesel engine; low temperature rheology of commercial base stocks; viscosity prediction for multigrade oils; comparative rheology of commercial viscosity modifier concentrates; the development of a thermo-oxidation engine oil simulation test (TEOST); and development of an on-board type oil deterioration system.
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Tribology of Engines and Engine Oils

Michael J. Covitch, Pawan K. Goenka, Thomas Morel, Simon C. Tung
  • Special Publication (SP)
  • SP-0959
Published 1993-03-01 by SAE International in United States
Tribology of engines and engine oils details all key aspects of tribology - rheology, friction, wear and lubrication, and all major tribological components of an engine including - bearings, pistons rings, and cam tappets. Contents include: diesel engine piston scuffing: a preliminary investigation; a simplified approach for cavitation prediction in hydrodynamic journal bearings; mechanical degradation of multi-grade engine oils; an experimental investigation of sliding at cam to roller tappet contacts; analysis of roller-follower valve gear; oil film thickness in engine connecting-rod bearing: comparison between calculation and experiment; experimental and numerical investigation of inter-ring gas pressures and blowby in a diesel engine; an integrated design analysis methodology to address piston tribological issues; piston-ring assembly friction modeling by similarity analysis; and fire ring wear analysis for a piston engine.