Automotive Engine Evaluations from Oil Filters

Road dusts, wear metal particles and any foreign objects, which make their way into the engine oil, are collected on the system filter. What collects on the filter can be used to indicate the type of service life that the engine has recently seen. All engines wear out and the type of wear metal particles, their shape, alloy composition and quantity are often graphic testimony to the overall service life which an engine has seen.

Over the past twenty five years our firm has been presented with oil filters from recovered "stolen" vehicles that have been burnt, driven into lakes, rivers or canals, completely "totaled" from collision, or the engines revved and loaded until they overheated and failed catastrophically through seizure and are destroyed. Vehicle owners often contend that the stolen vehicle engine was "in great shape, burnt no oil, started right up on the coldest morning, plenty of power, never a problem with it!" In most cases when we examine the filter and residual oil, they tell a very different story.

Road dusts, which are fine enough to pass through the air cleaners, tend to accumulate in poorly maintained engines. Chemical analysis and examination under the microscope of the accumulated particulate matter in the filter canister quickly identifies these contaminants. Road dusts are virtually absent in the oil filters of vehicles conscientiously maintained.

Regardless of how an engine was destroyed the residual oil left in the filter canister can also be a mirror of the past engine service life and an additional indicator of the conscientiousness of any preventative maintenance programs in effect. Wear metals monitoring programs work very well. In new oils there are only ultra low level traces of the elements monitored in a wear metals program and in a well maintained engine they are not allowed to build up. Long-term wear and poor maintenance produce high wear metal contents in the oil. Long-term wear is gradual and creates microscopically small particles, which are suspended in the oil and settle out over long periods of time. Sudden catastrophic failures from excess stress generate large torn metal fragments, which collect on the filter and are too large to be held in suspension by the oil. When engines suffering from long term wear and poor maintenance are destroyed by sudden catastrophic overload the accumulated residues from previous long term wear are still present in the oil and filter and are quite easily sorted from the short term damage residue.

There are no glycols in lubricating oils and water contents are very low. Water,glycols and paraffinic oils do not mix. Water entering the engine sump collects at the bottom of the pan. Sustained engine operation is required to force the water/glycol coolant and oil through the oil pump and into the hot engine bearings where under sustained heat and pressure the two can be forced to form a stable homogeneous material. The process requires long time periods or very heavy loading conditions to force glycols and water into the oil. Sudden catastrophic engine failures that result in the engine coolant contaminating the lubricating oil create temporary mixtures, which soon separate back into two components. Filters removed from vehicles, which have been submerged in lakes, canals or rivers over a winter season, still showed the clear evidence of emulsified glycol and water that resulted from extended engine operation with cracked heads and worn gaskets.

Automotive insurance adjusters are often faced with evaluating recovered stolen vehicles that have been damaged by fire or immersion. The condition of the engine in the vehicles prior to theft can often be determined by chemical and microscopic analysis of the oil filter contents. The results of mechanical inspections can often be confirmed or challenged by examination of the wear metals in filter cartridge and residual oil of the lubricating system.