A study of the tribological impact of biodiesel dilution on engine lubricant properties

S. H. Hamdan, W. W.F. Chong*, J. H. Ng, C. T. Chong, S. Rajoo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The switch from petro-diesel fuel to biodiesel blends for Compression Ignition engines have raised tribological performance concerns among major automobile manufacturers. Biodiesel dilution on engine lubricants could have adverse long-term effects on the engine efficiency, which will reduce the fuel economy, thus, leading to higher greenhouse gas emissions. Therefore, this study investigates the tribological impact of palm methyl ester (PME) diluted in SAE5W40 and SAE10W40 engine lubricants along different lubrication regimes under engine cold start condition. Through lubrication Stribeck curve analysis conducted using a pin-on-disc tribometer, coefficient of friction (CoF) for both engine lubricants showed parabolic maximum behaviour with increasing PME dilution. The CoF reduction beyond these peak values is attributed to the improved friction modifier effect from the now-dominant PME but with reduced load carrying capacity. An effective lubricant should possess both reasonable friction modifier effect and highest load carrying capacity in mitigating boundary friction. Hence, through the study, it could be deduced that the acceptable PME dilution threshold level for SAE5W40 is up to 17.5-vol%, while for SAE10W40 is between 28.0-vol% and 34.5-vol%. PME dilution levels beyond these thresholds could easily cause lubrication film rupture under high load, high shear rate conditions during application along the mixed to boundary lubrication regimes, inducing material wear.

Original languageEnglish (US)
Pages (from-to)288-297
Number of pages10
JournalProcess Safety and Environmental Protection
StatePublished - Nov 2017

Bibliographical note

Publisher Copyright:
© 2017 Institution of Chemical Engineers


  • Biodiesel dilution
  • Engine lubricant
  • Friction
  • Lubrication Stribeck curve
  • Palm Methyl Ester
  • Tribometer

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Chemical Engineering
  • Safety, Risk, Reliability and Quality


Dive into the research topics of 'A study of the tribological impact of biodiesel dilution on engine lubricant properties'. Together they form a unique fingerprint.

Cite this