Effect of Unleaded Fuel and Exhaust Gas Recirculation on Sludge and Varnish Formation

Stambaugh, R. L.; Kopko, R. J.; Franklin, T. M.

doi:10.4271/720944

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…Dispersancy: It has been pointed out that dispersant PMAs can replace a significant portion of the ashless dispersant necessary for sludge dispersancy performance in gasoline engines using either leaded or unleaded gasoline [83]. Significant varnish benefits were also noted by the use of dispersant or PMA VI improvers.…”

Section: Deposits: Diesel Piston Depositsmentioning

confidence: 97%

“…Several reports demonstrated that dispersant PMA or OCP VI improvers in some cases permit a significant reduction in ashless dispersant level for fully formulated engine oils, also permitting use of a heavier base stock [17,83]. The choice of shear stability level is also a major factor affecting the CCS viscosity, and therefore choice of base stock.…”

Section: Low-temperature Viscositymentioning

confidence: 99%

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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: 97%

Section: Low-temperature Viscositymentioning

confidence: 99%

Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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“…However, using a Sequence VC type procedure with Exhaust Gas Recirculation, Stambaugh et al, found TEL in the fuel had little effect on the level of sludge [54]. Significant amounts of Pb are carried through with blow-by into the sump as PbCl 2 , PbBr 2 as well as PbO, PbS0 4 and Pb(N0 3 ) 2 which will combine with the oil, water and oxidation products to form sludge or lead paint'.…”

Section: (Hi) Tetraethyl Leadmentioning

confidence: 99%