Having cleaner oil is better for the reliability of the engine. ¹⁾
There’s an old saying that oil doesn’t wear out; it just gets dirty.
Although there is some validity to the idea that dirtier oil will “age” quicker than clean oil,
The engine oil will have a finite life. It will need to be changed eventually no matter how clean you keep it.

• Filter ratings are the most often misunderstood area of contamination control. ²⁾
  • A nominal rating is an arbitrary size value assigned to a filter by the manufacturer.
  • Tests have shown that particles as large as 200 microns will pass through a nominally rated 10-micron filter.
  • Because the nominal rating is arbitrary, it has no value.

Often limited by physical size, engine oil filters are relatively small when compared to their industrial counterparts. ³⁾
This small size coincides with less filter media surface area through which to pass the lubricant.

In a case study performed by General Motors and published by the Society of Automotive Engineers (SAE);
It was determined that engine service life could be extended eight times when 5-micron filtration is implemented vs. the standard 40-micron filtration. ⁴⁾

• The oil filter media is the actual material used to capture contaminants in a filter element. ⁵⁾
  • Whatever media is used, it usually starts out in sheet form and is then folded or pleated to expose more surface area to oil flow.
  • This is done to increase contaminant carrying capacity and to reduce the pressure differential across the filter.
• The most common media: ⁶⁾
  • Wire mesh: constructed of either standard or stainless steel in a woven mesh.
    Because of the limitations in wire size and construction techniques, they are not available in very fine micron ratings.
  • Cellulose: made from wood pulp.
    The “paper” used for cellulose filters isn’t much more sophisticated than the paper used for writing.
    They are however cheap.
    The downside of this type of media is that it is not very efficient nor do they have a high dirt holding capacity. Cellulose also absorbs water, which may or may not be a benefit.
    They can be used to remove water from the system, however if this is not the desired effect and there is water in the system, the filter element will still absorb water.
    The pressure differential will increase and the filter will appear clogged.
  • Fiberglass: a type of synthetic filter media.
    In general, synthetic media performs considerably better than cellulose media because the fibers can be manufactured in a more uniform size distribution and thinner than cellulose media.
    Multiple layers of differing quality can be used to create a medium that is both extremely efficient and offers great dirt holding capacity.

• The media pore size is the major determinant in how efficient and how small of particles the filter can remove. ⁷⁾
  • The physical size of the filter is usually determined by the other components around it.
    The flow rate must be high enough to feed all the lubricated components.
    This means you can’t make the pore size too small or it will raise the pressure differential and the bypass valve will open, effectively rendering the filter useless.
  • In a case study performed by General Motors and published by the Society of Automotive Engineers (SAE);
    It was determined that engine service life could be extended eight times when 5-micron filtration is implemented vs. the standard 40-micron filtration.

• The pressure differential is the change in pressure from the inlet to the outlet side of the filter. ⁸⁾