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Lube-Tech No.80 page 1PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE

Modern Base Oils & Blending for Optimal PerformanceMeeting the Evolving Needs of theEuropean Lubricant MarketThe lubricants industry in Europe is at acrossroads. Historically, lubricant form-ulations have been based uponoptimising Group I, Group III or a GroupI/III blend with a proven additive package.

Relying on Group I and Group III hasserved the European lubricants industryexceptionally well. Group I is readilyavailable, and typically, is the leastexpensive base oil. Historically, it hasbeen the dominant ingredient in manylubricant formulations, particularlyindustrial lubricants and automotiveformulations with a lower viscosity index(VI). As a result, Group I has become the‘work horse’ base oil throughout Europe,whilst Group III has been used to deliverhigher performance and lower viscosity.

With tightening environmental legislationthis historical balance is beingchallenged. In order to meet ‘green’initiatives, the Automobile ManufacturersAssociation (ACEA) is pushing for tighterengine oil specification standards.

This has created a maze of OEMrequirements that call for emissionsystem protection and extended drainintervals from both Passenger Car MotorOils (PCMO) and Heavy Duty Motor Oils(HDMO). Meeting those specificationsrequires lubricants with lower viscosityand lower volatility.

In addition to tightening performancerequirements for crankcase lubrication,automatic transmission fluids, greasesand industrial oils are also facing tougherchallenges. Automatic transmissions are

being redesigned to boost fuel economyand are moving to fluids that can providefill-for-life performance. Greases arebeing subjected to higher loads, higherbearing speeds, and higher temperaturesthat require formulations with betteroxidation and thermal stability. Similarly,users of industrial lubricants want betterthermal stability and longer oil life.

Generally speaking, these performancetrends are calling for base oils that have • Higher VI to enable better fuel

economy and low volatility• Lower volatility for reduced oil

consumption• Practically zero sulphur• Excellent oxidation stability• High saturates content for improved

additive response

Whilst these new standards are verygood for the environment, they arecreating significant challenges forlubricant manufacturers who mustgrapple with optimising lubricantformulations for new specifications whilstmanaging supply chain cost andcomplexity. New premium quality baseoils will need to be added to the supplychain in order for blenders to meet thefull range of new specifications for their Automotive Engine Oils (AEO).

This means increasing tankage toaccommodate additional base oils or re-evaluating formulations across a blendersentire product line and identifyingopportunities for reformulating with newpremium base oils.

Careful selection of base oil suppliers willhelp reduce potential supply chaincomplexity and cost. Given the complicatedand costly process for qualifying lubricants,selecting base stocks from suppliers withlarge volumes and multiple plants helpsminimise the need for expensive requalifi-cation testing with alternative base stocks.This also reduces tankage requirements.These challenges have brought a newlevel of scientific sharing between OEMs,lubricant manufacturers, additivecompanies and base oil suppliers to findsolutions that optimise performance andmeet market demands.

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Lube-TechMeeting New Mid/Low SAPSRequirements – A Blending Challengefor Lubricant ManufacturersOf particular concern, is how to optimiseblending strategies for AutomotiveEngine Oils (AEO) in light of new specifi-cations. Group I base stocks are high inaromatics, sulphur and nitrogen, all ofwhich have a negative impact onlubricant performance. Historically, as theneed for improved product qualityincreased, some combination of theadditive treat rate and the amount ofGroup III were increased to compensatefor the impurities/inefficiencies in Group Ibase stocks.

In response to the introduction of Euro Vand VI emission regulations, OEMs havemodified their engine designs andemission control systems to reduce thelevel of nitrogen oxides and particulatesreleased into the atmosphere. One of thesolutions was to install after treatmentdevices, such as diesel particulate filters(DPFs) and selective catalytic reductionunits (SCRs).

Protecting the performance of thesedevices drove the need for newEuropean specifications that restrict thelevels of sulphated ash, phosphorous andsulphur (SAPS) in motor oils. In responseto these tightening standards, newcategories of “Mid and Low SAPS”engine oils have been designated.

Significantly, given the high amount ofsulphur in Group I base oils, they cannotbe used in AEO formulations designedfor Mid or Low SAPS specifications.This creates a significant challenge forproducers of 10W-XX and 15W-XXmultigrade lubricants, which account formore than 85% of the European finishedlubricant’s HDMO market. Group III alonehas insufficient viscometrics to meet theperformance requirements for heavier

motor oil grades and Group I has toomuch sulphur for the new specifications.

This is the crossroads for Europeanlubricant manufacturers. The challengelies in meeting the requirements for Midand Low SAPS lubricants whilst providingthe necessary performance for enginesrequiring 10W-XX and 15W-XXlubricants. This is particularly true forheavy-duty engines. Large diesel enginesare subjected to demanding workloads.They typically operate at low speeds andvery high torque. Their engines requirelubricants that provide sufficient hightemperature/high shear (HTHS) character-istics to insure adequate wear protectionand maximise engine durability.

To meet this challenge European blendersare evaluating the range of base oilsavailable and their impact onperformance and supply chaineconomics.

Alternative Base OilsThe ATIEL and API base oil classificationsystem groups base oils based on theirpurity and VI. It was established to helpmarketers minimise re-testing costs whenblending licensed engine oils with baseoils from different manufacturingsources. The system uses physical andchemical parameters to divide all basestocks (oils) into five Groups – Groups I.II, III, IV and V.

Base stocks, even in the same ‘Group’,may differ widely in their molecularcomposition, and physical and chemicalproperties depending on the feedstockand processing parameters used by therefiner. Differences in base stockcomposition affect the performance offinished lubricants, consequently, basestocks are considered non-fungible inmany lubricant formulations. This isparticularly true in high performance

automotive engine oils. As a result,supply reliability of fungible base stocksshould be a critical consideration in theearly stages of new lubricantformulations.

Where Automotive Lubricants go, Base Stock Characteristics goAutomotive lubricants demand morethan half of all base oil production.Additionally, they have strictrequirements for physical and chemicalproperties. So refiners, within thecapabilities of their processing scheme,design the physical and chemicalproperties of their base oil production tomeet the performance requirements ofautomotive lubricants.

Refiners can influence the characteristicsof their base stocks by feed stockselection, processing severity andcatalyst selection. But, by far, the mostsignificant limiting factor on base oilquality is the manufacturing processused by the refiner. There are twogeneral processing schemes forproducing mineral oil base stocks. Theolder process, solvent dewaxing wasdeveloped in the 1920s and is used forproducing Group I base stocks. Thesecond, an all-hydroprocessing schemeChevron introduced in 1993 usesisomerisation for dewaxing. It is used tomake Group II/III base stocks.

Group I Base Stocks – Excellent for many industrialapplications, but too much sulphurfor tightening AEO specificationsProducing Group I base stocks starts withvacuum gas oil (VGO), one of the heavierstreams coming out of the crude unit.Solvents are used to selectively remove50-80% of the impurities. However, thetreated base oils stream still has paraffinsthat need to be removed to produceusable base stocks.

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The paraffins are removed by a dewaxingprocess that uses solvents taken to a lowtemperature, where the wax is precipitatedout. The resulting Group I base stock hasrelatively high sulphur making it unsuitablefor Mid and Low SAPS AEO specifications.

Group II/III Base Stocks – All-hydroprocessing technologyAll-hydroprocessing for base oils startswith the same feed as a solvent plant.However, instead of using a solvent toremove undesirable compounds, the feedis processed in a high-pressure hydro-cracker with catalysts that reshape themolecules, saturate the aromaticcompounds and create high quality isoparaffins. In total, 98-99.9% of theimpurities are converted to high qualitybase oils. Chevron invented thisprocessing scheme in the 1990s andtoday more than two thirds of theworld’s premium base oil is producedusing this upgrade path.

Whilst the same upgrading technology isused for producing Group II and Group IIIbase stocks, the driver for which grade arefinery produces is the source of thefeed - a large diesel hydrocracker vs agasoline hydrocracker.

Group II is typically produced byprocessing VGO in a dedicated base oilhydrocracker in a gasoline refinery.Group III is primarily produced byprocessing unconverted oil (fractionatorbottoms) from a two-stage diesel hydroc-racker. Whilst any diesel hydrocrackercan make some Group III feedstocks,they are most efficiently produced inlarge-scale diesel hydrocrackers.

Given the direct correlation betweenfuels production and base oil grade(Group II vs. Group III), regional base oilproduction capacity correlates signifi-cantly with regional fuels demand.

Regions with high diesel demand aremore likely to have high Group IIIproduction, whilst gasoline producingregions favour Group II production.

The principal difference between Group IIand Group III base stocks is VI. They areboth premium base oils containing lessthan 10% aromatics and less than 300ppm sulphur as defined by API publication1509. They typically have about 1%aromatics or less and almost undetectableamounts of sulphur. As a result, thesebase oils have better oxidation stability,thermal stability, and cold flow propertiesthan Group I base oils.

Group III+ GTL Base Stocks The first large-scale GTL base oil plantstarted up in 2011. It uses the samehydro-isomerization process as that usedto produce Group II and Group III baseoils. Like its Group II and Group IIIcounterparts, GTL base stocks haveexceptional thermal and oxidativestability. What distinguishes them fromother hydroprocessed base oils are theirhigh VI of 135-145. Consequently, GTLbase stocks are classified as Group III+,an unofficial API category that recognizestheir higher VI than other Group III basestocks.

Whilst GTL base oils have had consid-erable coverage in the industry press,they have limited availability.

Group IV/V Base Stocks –PAOs,Synthetics and All OthersPolyalphaolefins (PAOs) have excellentperformance properties and are wellproven in many demanding formulations.However, they are a synthetic byproductderived from processing crude oil. Acomplex manufacturing chain is requiredfor their production.

Manufacturing PAO starts with anethylene cracker making the simplestolefin (ethylene) from hydrocarbon feeds.The primary cracker feed is naphtha.Ethylene is selectively polymerized intolinear alphaolefins (LAOs). The heart ofthe LAO production is C4, C6 (~16%),C8 (12-13%), and drops off to about10% for C10 and 8% for C12. Thelighter alphaolefins, C4-C8 cuts, arecomonomers for plastics, whilst the C12-C16 cuts typically go into detergents andthe very heavy ones -- >C24 go intospecialty applications.

The C8, C10 and C12 LAO can beoligomerised into Polyalphaolefins (PAO).Most C8 goes to comonomer for plastics– only a little goes to PAO. PAO isprimarily made from C10 LAO.Additionally, PAOs require a finalhydrotreating step to fully saturate thedouble bonds. Given the competition forfeedstock and complexity of the PAOproduction process, PAO supply willcontinue to be limited and relativelycostly. As a result, its use will be confinedto operating environments withexceptionally high or low temperatures,or circumstances requiring excessivelylong lubricant life - like space travel orwind turbines.

New boutique base oils entering themarket, including those from vegetableoils, sugar cane, and re-refined basestocks, have a broad quality range.Whilst some of these base stocks have

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excellent performance properties they areall constrained by limited productioncapacity. Consequently, they will be usedin niche applications with limited volumedemands.

Adequate and Reliable Supply is aBase Oil Prerequisite for MeetingNew Mid/Low SAPS AEOSpecificationsThe challenge confronting lubricantmarketers is how to capitalise on therange of base oils available to optimiseformulations for changing specifications.

After reviewing the base oil alternativesfor meeting new Mid and Low SAPSperformance specifications, the optimalchoice is Group II base oils. They havepurity comparable to Group III basestocks plus the necessary viscosity foradequate wear protection in enginessubjected to heavy duty work loads.Most importantly, they are now availablein Europe in sufficiently large volumesfrom more than one supply source.

In practical reality, the questionconfronting European lubricant blenderswho market a full range of automotiveengine oils, is not whether they willintegrate Group II base oils into theirprocessing scheme, but when and how?

Optimising Blending With AvailableSupply Becomes the Next ChallengeTypically, lubricants use two base oilswith different viscosity grades to achievea desired viscosity level. New specifi-cations may require the use of a thirdbase stock as a ’correction fluid’ to meetcold crank simulator and (CCS) andvolatility (Noack) requirements.

Blending chart plots showing base oilNoack volatility plotted against ColdCrank Simulator (CCS) - a measure ofviscosity at low temperature – are an

effective and efficient way for identifyingoptimal base oil blends. If different ratiosare blended you end up with a curveshowing volatility at a given viscosity.Group II has a broad spectrum ofperformance that meets much of theblending requirements for 5W-XX or10W-XX lubricants. The curvesdemonstrate increasing blending quality.

Group II/II+ Base Stocks Can Meet theNeeds of the Majority of EuropeanFormulationsThe European PCMO market is highlyspecialised with sub-segmented markets.These are defined by performance levelswithin different viscosity gradesprescribed by industry and OEM specifi-cations. Consequently key base oilproperty requirements vary considerablyfrom one OEM’s performance level toanother. This has led to differing degreesof Group III content in mainline andpremium automotive formulations andreflects the region’s history of Group Iand Group III base oil availability to theexclusion of Group II base oil.

Most of the automotive engine oilvolume, both for heavy duty andpassenger car segments, can be blendedwith the majority component beingGroup II and/or Group II+. In many cases,this blending strategy brings both costand performance benefits.

Major formulators in Europe have beendeveloping Group II blends for the lastthree years, plus all of the major additivecompanies have experience in NorthAmerica optimising lubricantperformance with Group II base oils inboth industrial and engine oilapplications.

Group II/II+ can meet Europeanautomotive performance specificationsfor all but the lightest grades such asextremely low volatility 5W-XX and 0W-XX grades.

As with any new product, formulatorswill need to determine the optimalviscometrics and volatility requirementsfor the base oil blend that is required for the specific additive system to be used.Through precise formulation work thelevel of Group III can be optimised, or insome cases, eliminated completely,leading to formulation cost savingswithout compromising performance.

Through optimisation with Group II basestocks, blenders may realise a reductionin additive treat rates for Group II blendsversus Group I blends.

Formulating work completed with themajor additive companies has shownthat Group II/II+ base oils are an excellentalternative for producing 10W-40 and5W-30 lubricants. 10W-40 PCMOformulations typically include between20-50% Group III base oil with the remainder being Group I.Comparable performance can beachieved with an optimised blend ofGroup II and Group II+ base oils.

This formulating scheme eliminates theneed for both more costly Group III andless pure Group I base oils. Similarly 5W-40 PCMO lubricants, which typicallyrequire 100% Group III, can beeffectively formulated with a blenddominated by Group II+ with Group IIIused as a trim stock to meetperformance requirements for a givenspecification.

For lubricant manufacturers, oxidationstability is a critical component of theirformulating objectives. The better thelubricant’s oxidative stability, the betterthe lubricant’s ability to minimisedeposits, sludge, and corrosive

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By graphically displaying the performance range of base oil blends, one is able to identify the most efficient blend for meetinga desired performance objective. How it is done:

• Curves are created by blending two base stocks in varying ratios

• Target base oil blend viscosity and volatility is established by backing out contributions from additive and VM packages

• If curve lies below the target, the blend of the two base stocks is capable of meeting or exceeding the volatility andviscosity requirements

• In some cases, a correction fluid is required because only 2 blend components cannot meet either the CCS or the Noackvolatility.

To hit the indicated Base Oil Blend(BOB) target, an optimised blendwould use only 220N andChevron 110RLV (Group II+).Case 3, as a ‘Dumbbell Blend,’ isprobably the weakest of the baseoil blend alternatives. It contains avery high percentage of highvolatility 100N oil and may havedifficulty passing hightemperature engine tests

Example 1Optimising the base oil blend for an E9 10W-40

All 3 cases meet the samevolatility and CCS requirementsbut have different formulatingcosts. However, if a lower Noackand CCS are required, theblending diagrams directionallyshow the preferred correctionfluid. Again, Case 3 is a weakblend alternative.

Example 2Identifying the preferred correction fluid for A3/B4, 5W-30

If just a lower Noack is required,the obvious correction fluid is 8cSt Group III. However, if both alower Noack and CCS are desired,the blending diagramsdirectionally show the preferredcorrection fluid is still 8cSt.

Example 3dexos™ 2 – 5W-30 PCMO base oil blend needs to have lower volatility and possibly CCS

Graphic diagnostic tool identifies optimal blending ratios

byproducts in grease, engine oil andindustrial oil applications. Additionally,lubricants with high oxidative stability aremuch less likely to undergo undesirableviscosity increase during the life of the oil.

The performance of five differentlubricants blended with the sameadditive package, but alternative Group IIand Group III base oils, were comparedon the Sequence IIIG test. It is a verytough test designed to simulate a vehiclepulling a heavy load across a hot desert,and is the cornerstone of the API GF-4/SM service category.

All of the formulations passed easily withone of the Group II blends performingcomparably well with the Group IIIformulations.

Group II – An Excellent Alternativefor Industrial OilsThe excellent oxidation stability of GroupII base oils can be leveraged forsignificant performance improvement inindustrial oils as well.

When Group II based turbine oils aresubjected to a TOST test, Turbine OilStability Test (ASTM D946, D5846), thereis substantially less viscosity increase inthe oil than with Group I formulations.So much so, that the standard ASTM D943 TOST test for turbine oils was

modified to accommodate the extendedperformance of the Group II base oils. Bydecreasing the sample withdrawalvolume from the test oxidation cell byhalf, one can extend the maximum testrun time from 10,000 to 20,000 hours.Thus, the Group II base oils extendedturbine life by more than 300% to 2.5years. This performance is comparable toGroup III base oils at a lower totalformulation cost.

New Chevron Pascagoula PlantAdding 25,000 Barrels per Day toChevron’s Global Supply NetworkWith the world demanding moreenvironmentally sustainable behaviorfrom its industries and transportationsystems, Chevron committed to buildinga new 25 KBPD (1.25 Million TPA)premium base oil plant at its refinery inPascagoula, Mississippi.

Chevron’s refinery system will beproducing consistent quality premiumbase oils from each of its refineries.Global availability will be augmented bya network of strategically locatedregional supply hubs. The Pascagoulaplant is scheduled to come on line in late2013. Its product slate was designed tomeet the global quality and performanceneeds of both premium and mainlinelubricant products. The majority of theproduction will be high quality Group IIbase stocks.

Chevron's premium base stocks cansatisfy some of the most stringentlubrication applications as well as meetcritical OEM specifications for bothautomotive engine oils as well asindustrial oils.

Summary As performance standards tighten, theimpurities of Group I base stocks willmake them unacceptable in many engineoil formulations. This is already evident inapplications required to meet Mid andLow SAPs formulations in Europe.

The use of PAO and other boutique baseoils will be confined to operatingenvironments with exceptionalperformance demands coupled with lowvolume needs due to their limitedproduction capacity.

As Europe moves into compliance withEuro VI emission standards, Group II baseoils will become a critical component inthe European market.

Group II/II+ base stocks have betterviscometrics and volatility than Group I/IIIblends enabling formulaic optimisation.In some cases additive treat rate can bereduced whilst still meeting toughspecifications for Mid and Low SAPslubricant packages. Additionallyformulating costs for current high SAPSspecifications such as ACEA A3/B4,ACEA E4 can be lowered.

With the addition of the Pascagoula baseoil capacity there will be an adequatesupply of globally available Group II andGroup II+ base oils with consistentquality.

LINKwww.chevronbaseoils.com

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