Importance of engine oil analysis

GME / GMPT-E EngineeringLubricants Russia, 23-25th November 2005, Moscow

1E. Leber, M. Seemann,R. Bütehorn,

Importance of Engine Oil Analysis for the Automotive Industry -Impacts and Evaluation of Chemical Results

Lubricants Russia, 23-25th November 2005

Edwin Leber, GME Engineering, Central Laboratories




Content

• Reasons for the need of oil analysis

• Significant analysis parameters for engine oils- Test methods and equipment- Influencing parameters

• Practical examples from field and bench tests

• Summary




Reasons for the need of oil analysis

• Engine development / Monitoring of bench and fleet tests

• Definition of oil change interval

• In-country validation (export regions)

• Quality assurance / Incoming inspection control

• Trouble shooting / Customer complaints




GM Europe

Oil type:Oil top up volume:

Test:Test period:

Milage oil:Milage Engine:

Transmission:Car No.:

Engine type:Date

Engine oil sample

Oil type:Oil top up volume:

Test:Test period:

Milage oil:Milage Engine:

Transmission:Car No.:

Engine type:Date

Engine oil sample GM Europe

Significant analysis parameters for engine oilsPrerequisite for reliable results and assessment:• Representative oil samples• Sampling according defined GME procedure• Reporting and monitoring of oil sample history• Oil consumption, top-up etc.




Significant analysis parameters for engine oilsTBN

• TBN (total base number ) mg KOH / g- defines the remaining alkaline capacity to neutralize acids

- Usually decreases by acidification due to blow-by gas,.NOx, SO2

- Increase possible by additive concentration due to evaporation

• Significantly influenced by vehicle driving conditions, (short or long trip)

• Determination by potentiometric titration

Comparability for results with identical method only



Potentiometric TitrationPotentiometric Titration

Acidic components react with titration reagent. Acidic components react with titration reagent. Electrodes measure change of pH / voltage continuously. Electrodes measure change of pH / voltage continuously.

Inflection point of resulting titration curve enables calculatioInflection point of resulting titration curve enables calculation of alkaline n of alkaline concentration concentration




Significant analysis parameters for engine oils

ViscosityKinematic [mm²/s] Dynamic [mPa·s]

• Important parameter to characterize flow properties of oils

• Definition of SAE class e.g. 5W-30, 5W-40

• Significant dependence on temperature (Viscosity Index VI)

Increase Decrease- Evaporation - Shearing of instable VI- improver- Oxidation/Nitration - Fuel dilution- Soot - Top up with diff. viscosity class- Top up with diff. viscosity class



Automatic measurement by conductivity or

optical sensors with final cleaning of

capillaries

Sample No.

Results

Instrumentoperation status





SootSoot• mainly important for Diesel engines

• significantly influenced by- driving conditions (load)- Engine hardware, (injection system, EGR, etc)

• Impact of high soot level on

Viscosity increase and wear

• Determination by Infrared Spectroscopy (FT-IR)





Nitration / Oxidation

• main issue for gasoline and CNG engines

• significantly influenced by- operating conditions e.g. load, temperature, EGR

• Engine hardware (e.g. ventilation system, oil cooler)

• Potential of sludge formation in case of insufficient anti-oxidative capacity

• determination by Infrared Spectroscopy (FT-IR)



Oxidation and Nitration are evaluatedIR-Spectra of an used

engine oil

Nitrationat 1630cm-1

Oxidationat 1710cm-1





Fuel DilutionInfluenced by

• Driving conditions, cold start, oil temperature

• Engine hardware- Diesel Particle Filter with post injection regeneration- Gasoline Direct Injection

• Various simplified indirect methods applied, e.g. Viscosity, Flashpoint

• high uncertainty especially for unknown matrixSophisticated gas chromatography (Simulated Distillation) is best approach, DIN 51 435/2



Simulated distillation for determination of boiling range of

fuels & oils.

This enables to calculate e.g. fuel dilution in engine oil.

Gas chromatograph Gas chromatograph



Diesel Fuel dilution Chromatogram engine oil with fuel dilution

FAME content





Metal / Element contentsophisticated equipment enables fast multi-element-analysis:

• XRF X- Ray Fluorescence analysis - very fast, no sample preparation- not applicable for Lithium, Boron and traces

• ICP-OES Inductive Coupled Plasma Optical Emission Spectroscopy- applicable for traces and elements not covered by XRF - Sample preparation required (dilution)




OriginElement additive wear fuel coolant polymers

conta-mination

processlubricants

Iron • •Aluminium • •Copper • •Tin •Lead • •Silicon • • • • • •Zinc • • • •Calcium • • •Magnesium •Molybdenum • • • •Phosphorous • •Sulfur • • • •Sodium • • • • •Potassium • •Chlorine • •

Significant analysis parameters for engine oilsMetal / Element sources



XRF= X-Ray Fluorescencedetermination of element concentration in liquid and solid samples. No sampling preparation.

Not appropriate fore.g. B, Li, tracesPrinciple of X-ray

analysis




F U E L D IL U T IO N in d i f fe re n t d r iv in g c y c le sC ity C y c le v s . H ig h w a y c o n d it io n s D I D ie s e l e n g in e w ith D P F

0

1

2

3

4

5

6

7

8

9

1 0

1 1

1 2

1 3

0 5 .0 0 0 1 0 .0 0 0 1 5 .0 0 0 2 0 .0 0 0 2 5 .0 0 0 3 0 .0 0 0 3 5 .0 0 0 4 0 .0 0 0 4 5 .0 0 0 5 0 .0 0 0O il m ila g e [k m ]

Fuel

dilu

tion

DIN

51

435/

2 [w

t%]

C ity C y c le

H ig h w a y

• DPF application could cause significant fuel dilution under specific driving cycles • Engine durability requires reduced oil change interval for these cases• Oil life monitoring-system calculates appropriate change interval




S O O T a c c u m u la tio n in d iffe re n t d riv in g c yc le sH ig h w a y vs . B e n c h te s t c o n d itio n s in D I D ie s e l e n g in e s

0 ,0

1 ,0

2 ,0

3 ,0

4 ,0

5 ,0

0 1 0 .0 0 0 2 0 .0 0 0 3 0 .0 0 0 4 0 .0 0 0 5 0 .00 0O il m ilag e [km ]

Soot

con

tent

DIN

51

452

[wt%

]

S oo t H igh w a y

S oo t B e nc h tes t

• Worst case simulation with e.g. high load, EGR rate on engine bench test possible • Controlled oil consumption• Reduction of cost intensive fleet test




T B N d e c r e a s e d e p e n d e n t o n f u e l q u a l i t yL o w v s . H i g h s u l f u r f u e l i n D I D i e s e l e n g in e s

0

1

2

3

4

5

6

7

8

9

1 0

1 1

1 2

1 3

0 5 . 0 0 0 1 0 . 0 0 0 1 5 . 0 0 0 2 0 . 0 0 0 2 5 . 0 0 0 3 0 . 0 0 0 3 5 . 0 0 0 4 0 . 0 0 0 4 5 . 0 0 0 5 0 . 0 0 0O i l m i l a g e [ k m ]

TBN

, DIN

ISO

377

1 [m

gKO

H/g

]

h i g h s u l f u r f u e l ( 5 0 0 0 p p m )A C E A A 3 / B 3 o i l q u a l i t y

s u l f u r f r e e f u e l ( < 1 0 p p m )G M - L L - A - 0 2 5 o i l q u a l i t y

• Lower oil and fuel quality in export countries need compensation by reduced oil change intervals

EU 25 EU 25

30.000 km / 1 Year

15.000 km / 1 Year

7.500 km / 1 Year

30.000 km / 1 Year

15.000 km / 1 Year

7.500 km / 1 Year

GM-LL-A-025 ACEA A3 / B3 API SL / ILSAC GF3API SM / ILSAC GF4 GM-LL-B-025 ACEA A3 / B4 API CI - 4 /

API CH - 4

Oil Change Interval Gasoline Engines Oil Change Interval Diesel Engines

Export Export




TBN decrease dependent on driving profileCity Cycle vs. Highw ay in M PFI Gasoline engines

0

1

2

3

4

5

6

7

8

9

10

11

12

13

0 5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000Oil m ilage [km]

TBN

, DIN

ISO

377

1 [m

gKO

H/g

]

City Cycle

Highway

• City Cycle is “worst case” regarding engine oil degradation for gasoline engines • Important for oil change interval validation• Basis for Oil life monitoring to adjust drain intervals to driving conditions




Summary / Conclusion

• Experience and expert know-how is pre-requisite for evaluation of results regarding- Base oil quality and Additive technology - Engine and after treatment technologies- Periphery (coolant, fuel, grease, oil filter etc.)

• GME/GMPT Global team of hardware and oil experts established

Close link to: - Mineral Oil and Additive Industry, Independent Test Labs- ACEA, CEC, VDA etc.

• Importance of oil analysis requires sufficient in-house capacitiesand continuous optimization of equipment and test methods



Thanks to my coauthors for their great support:Reinhard Bütehorn, GM Powertrain-EuropeMichael Seemann, GME Engineering

Many thanks for your attention!

Importance of engine oil analysis

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