Oil analysis - What is it and why should we do it?

Carrying out regular oil sampling and analysis can help identify problems before they become really expensive to repair.

Oil analysis involves the sampling and analysis of engine, hydraulic and transmission oil to determine the level of wear of components and contamination of the oil. Early detection of problems can reduce repair costs, prevent catastrophic failures, increase machine life and reduce non-scheduled downtime. One can also identify problems without having to dismantle a component. The greatest advantage is being able to predict problems and address them early. This should therefore be part and parcel of any good preventative maintenance programme.

When taking an oil sample, the oil should be hot and properly mixed. If the oil is not properly mixed the sample results could be skewed. The best time is when oil is being drained during an oil change or service. Samples can also be obtained by inserting a plastic tube down into the sump or reservoir.

The costs of oil analysis vary from place to place, but are guaranteed to provide considerable savings in the long term. No two machines are exactly the same and are operated under different conditions. Therefore, different parts will wear differently on each machine. Preventative maintenance programmes are usually based on certain actions at specific machine hours. Oil analysis allows more accurate predictions of when maintenance should be carried out. It could be that an operator is changing oil too soon, or carrying out maintenance too often.

Some of the more important properties that oil is analysed for include:

 

  • Fuel dilution of lubricating oil – thins oils, lowers lubricating ability, lowers oil pressure and increases wear.
  • Total solids – such as ash, carbon and oil oxidation.
  • Antifreeze in the oil – reduces oil flow, leads to oxidation, oil thickening, high acidity and eventually engine failure.
  • Oxidation – looks at gums, varnishes and oxidation products. This can occur from oils used too hot or for too long.
  • Total base number – measures the acid-neutralising capacity remaining in the lubricant.
  • Viscosity – measures the oils resistance to flow. Oil that is too thin or too thick is problematic.

Various metals are tested for. The presence of any of these metals in significant quantities can pinpoint in which components a problem may be.
Source: www.bobistheoilguy.com Image: www.kittiwake.co

Return to Articles