Low-Temperature Pumpability of U.S. Army Diesel Engine Oils

Frame, E.A.; Montemayor, Alan; Owens, E.C.

doi:10.4271/892053

Cited by 10 publications

(1 citation statement)

References 26 publications

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“…This was confirmed with the additional observation that VI improver differences in performance were minimized for engines properly designed for low-temperature flow [87]. VI improvers' chemistry rankings were confirmed in a program which studied engine parameters further and included a broader range of SAE W-grades [88], supported by very similar observations for heavy-duty diesel engines [89,90].…”

Section: Low-temperature Viscositysupporting

confidence: 62%

Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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The viscosity index of an oil or an oil formulation is an important physical parameter. Viscosity index improvers, VIIs, are comprised of five main classes of polymers: polymethylmethacrylates (PMAs), olefin copolymers (OCPs), hydrogenated poly(styrene-co-butadiene or isoprene) (HSD/SIP/HRIs), esterified polystyrene-co-maleic anhydride (SPEs) and a combination of PMA/OCP systems. The chemistry, manufacture, dispersancy and utility of each class are described. The comparative functions, properties, thickening ability, dispersancy and degradation of VIIs are discussed. Permanent and temporary shear thinning of VII-thickened formulations are described and compared. The end-use performance and choice of VI improvers is discussed in terms of low-and high-temperature viscosities, journal bearing oil film thickness, fuel economy, oil consumption, high-temperature pumping efficiency and deposit control. Discussion of future developments concludes that VI improvers will evolve to meet new challenges of increased thermaloxidative degradation from increased engine operating temperatures, different base stocks of either synthetic base oils or vegetable oil-based, together with alcohol-or vegetable oil-based fuels. VI improvers must also evolve to deal with higher levels of fuel dilution and new types of sludge and also enhanced low-temperature requirements. IntroductionThe 'viscosity index', VI, was an important measure of quality early in the history of the lubricants industry, indicating an oil's potential applications over a wide range of temperatures, described in Section 1.3.2. Pennsylvania grade oils,~100 VI, were the standard against which all others were measured. Hydrogenation and solvent extraction processes were developed to upgrade lubricants from poorer quality crude oils, but the practical VI ceiling for 1930s refinery technology was~110-115.Early workers found that small amounts of rubber dissolved into mineral oil substantially raised VI; however, high levels of unsaturation in the polymer led to oxidation and sludge formation. This was overcome by using a synthetic polymer prepared from gasoline light ends [1], and similar behaviour was later described for 153 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,

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Section: Low-temperature Viscositysupporting

confidence: 62%

Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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Low Temperature Pumpability in Gasoline Engines: Establishing Performance at Critical Locations

Machleder

O'Mara

Kopko

et al. 1992

Low Temperature Lubricant Rheology Measurement and Relevance to Engine Operation

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An extensive series of low temperature cold room pumpability studies has been conducted in gasoline engines. Much of the work, although focusing on the role of the Viscosity Index (VI) Improver in SAE 5W-30 and SAE 10W-30 engine oils, has also addressed the issue of measuring oil performance at critical engine locations. In anticipation of an industry-wide re-evaluation of low temperature engine oil pumpability, it is hoped that this work can help the industry refine the Mini-Rotary Viscometer (MRV), and other bench test procedures. A correlation with critical oiling, rather than the generation of oil pressure at the oil sensor light location which is the basis for the pumpability component of the SAE J300 classification, would improve the system. It is clear from this work that the time to generate oil pressure at the oil filter is considerably shorter than the time it takes to generate oil pressure, or oil flow, at critical locations downstream. It is also clear that oil formulation plays a significant role in the low temperature pumpability performance. The engines evaluated in this work were a 2.2 L I-4 OHC, a 2.3 L I-4 OHC and a 3.8 L V-6 push rod engine.

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