A New Look At Multigraded Diesel Engine Oils

Smith, M. F.; Tunkel, N.; Bachman, H. E.; Fernandez, W.

doi:10.4271/760558

Cited by 11 publications

(1 citation statement)

References 12 publications

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“…Early in the development of multigrade diesel engine oils, it was reported that the VI improver content in a formulation was a significant factor in contributing to piston deposits [102,103]. Since it is generally accepted that all VI improvers contribute to these deposits, the importance of keeping the VI improver content as low as possible was emphasized.…”

Section: Deposits: Diesel Piston Depositsmentioning

confidence: 99%

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: Deposits: Diesel Piston Depositsmentioning

confidence: 99%

Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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Hoult

Shaw

1994

Tribology Transactions

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British Rail Switch to Multigrade

Morley¹,

Eland²,

Dunn³

1984

Industrial Lubrication and Tribology

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British Rail uses more than 700m litres of fuel oil a year for diesel traction engines. Successive oil crises gave impetus to the development of multigrade oils which would achieve fuel economies in the diesel engines. Since no data was available on possible benefits of multi‐grade oils in large, medium‐speed diesel engines, it was necessary for BR to pioneer developments in this application which imposes special constraints on the formulations.

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A New Look At Multigraded Diesel Engine Oils

Cited by 11 publications

References 12 publications

Viscosity Index Improvers and Thickeners

Viscosity Index Improvers and Thickeners

The Puddle Theory of Oil Consumption©

British Rail Switch to Multigrade

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