Scientists - Sayles and MacPherson conducted a study to determine the life of bearings, a common and important component in all automotive, aeronautical and industrial machinery. Your engine and transmission consist of hundreds of similar bearings or components to those tested. The results of their study showed that the approximate thickness of the oil in the bearings was 3-10 microns. It also showed that most filtration was only at levels of 40 micron, like your transmission or engine spin-on filters. BUT if you could filter the oil of contaminants down from 40 microns to 3 microns there was a seven-fold increase in the life of the component.


Oklahoma State university reported in their study that when fluid is maintained 10 times cleaner, hydraulic pump life can be extended by 50 times. Most vehicles have a power steering pump and some have additional pumps powering other hydraulic applications, all of which are subject to failure from the small iron particles circulating in the fluid.
Fitch, E. C. "An In-line Contaminant Monitor for Fluid Power and Lubrication Systems." The Fluid Power Research Center, OSU. 1982.


AC Delco Division of General Motors also tested DDA [Detroit Diesel Allison] engines and found an eight-fold improvement in wear rates and engine life with lower lube oil contaminant levels. In a related study on both diesel and automotive engines, General Motors reported that "... compared to a 40-micron filter, engine wear was reduced by 50% with 30 micron filtration. Likewise, wear was reduced by 70% with 15 micron filtration."


Levels of Metal Contamination
In an SAE [Society of Automotive Engineers] paper, engineers John Eleftherakis and Ibrahim Kahil conducted an extensive study to define, quantify and describe the contaminants found in automatic transmissions. The study consisted of collecting oil samples from various mileage vehicles and found that 4 different materials were contributing over 90% (by weight) of contaminants found in vehicles with mileages from 70,000 to 120,000 miles.

These contaminants were:

The study also showed that over 97% (by number) were less than 10 microns in size.

The authors have been responsible for over 4,000 automatic transmission valve tests over the past 15 years and in another SAE study titled Optimizing Automatic Transmission Filtration concluded that "the particle removal efficiency of common transmission sump filters was shown to be unable to remove many of the most damaging particles, which result in transmission valve sticking, wear, and general shift quality degradation."


Three types of contaminant related failures have dominated the problems found. These are failures due to locking and or seizure [termed contaminant sensitivity] due to small particles (below 50 microns); durability failures due to the whole distribution of particles over a long time (termed contaminant wear); and catastrophic failure due to the jamming of large particles in metering devices (termed contaminant jamming). It must be remembered that these valve tests were on fluid that had already passed through the sump filter in the transmission before they had caused catastrophic and other failure modes.

Eleftherakis, John G & Khalil A: "Development of a Laboratory Test contaminant for Transmissions" SAE 900561, and "Optimizing Automatic Transmission Filtration" SAE 99PC-418.

Laboratory and field tests have shown that the most damaging metal particles are the ones that jam within the thin film of oil that cushions vital parts


Laboratory tests have proven the benefits of magnetic filtration