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Turbocharger Failure Series.

This month we’re looking at oil contamination as the cause of failure with your turbocharger. This is a significant issue we see quite regularly – typically where vehicles have not been serviced correctly and/or wrong grades of oil have been used.

Oil sampling is something we use quite commonly in the commercial sector as this can pick up on any underlying issues quickly before they become bigger problems. This can save fleet operators a lot of time and money. It’s not something that’s often done in the passenger car market but when we see regular turbo failures it’s something we highly recommend.

Think of an oil sample as a blood test.

Example: we had a Mazda CX5 diesel in a few weeks ago with the Garrett 2 stage turbo setup. The turbos had failed. After stripping the turbos, we could see heavy scoring to the bearing and thrust system on both turbos. After further digging we found out that the camshaft lobes had worn up to 3mm. This material was then transferred into the oil system and made its way through the turbochargers – destroying them. Although this was not good news for the owner it could have easily been overlooked and new turbos just thrown at it which would have failed again in the same fashion.


If you have missed the first two articles about foreign object damage and Blocked DPF’s these can now be viewed here.

What is Oil Contamination?

Oil is often overlooked as a critical component. However, clean filtered engine oil is a major requirement and a necessity for all turbochargers.

Causes of Oil Contamination

  • If the oil filter is damaged or a poor-quality oil filter is used.
  • Excess moisture can lead to premature oil degradation, increased corrosion, and increased wear.
  • High carbon build up present in the engine can quickly contaminate new oil.
  • Contamination of new oil whilst servicing (accidental).
  • Unchanged oil containing detergent deposits can become very abrasive to the turbos precision components.
  • Engine wear, which can leave swarf deposits in the oil.
  • Degrading oil caused by excessive temperatures or extended service intervals.
  • Internal engine leaks, such as fuel or coolant mixing with oil supply.
  • Residue from blasted components, during the remanufacturing process.
  • Particles from carbon build up in oil feed pipes.

Preventing turbo failure caused by oil contamination

  • Using new oil and filters helps to reduce the risk. We advise that filters recommended by the engine manufacturer are used when refitting the turbo.
  • Replacing or cleaning the oil inlet pipes and in-line micro filters helps to prevent carbon deposits entering the oil flow to the bearings.
  • Take care when changing oil during servicing to prevent accidental contamination.
  • Check for engine wear that could leave swarf deposits.
  • Check the vehicle is up to date with services.