Comments on: The Oil Filter http://www.ret-monitor.com/articles/871/the-oil-filter/ Specific mission-critical info for professionals Mon, 21 May 2012 22:46:19 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Terry http://www.ret-monitor.com/articles/871/the-oil-filter/comment-page-1/#comment-6161 Terry Thu, 20 Jan 2011 07:17:04 +0000 http://www.ret-monitor.com/articles/871/the-oil-filter/#comment-6161 With a production automotive engine, the oil filter captures debris particles down to a certain average size and shape. This is characterized by the filter beta ratio. The filter can also remove moisture from the oil. The heating and cooling cycles of the engine produces condensation in the crankcase air, and this condensed moisture collects in the oil and on surfaces in the crankcase such as the steel crankshaft, resulting in corrosion. With a race engine, moisture in the oil is not likely a concern, since the engine oil is replaced often. In other types of lube system filters, such as those used in aircraft gearboxes, the oil is filtered to a very high level of cleanliness. Typically about 3 microns or less. The reason for this is that a debris particle below 3 microns in size will pass through the hydrodynamic oil film contacts in the gear tooth meshes and rolling element bearings without causing any surface damage. Automotive engine oil filters don't filter to this level, since the filter element would need to be unacceptably large for a reasonable pressure drop. Having an oil filter on a race engine does provide some benefit. Since race engine components tend to fail on a regular basis, the filter will remove the debris from the failed components from the oil and usually allow the engine to keep running for a while longer. The downside to having an oil filter is the additional weight and complexity. With modern production engines, there is not much wear debris generated after an initial run-in period. The oil contaminants are mostly due to combustion blow-by, moisture and corrosion. With a production automotive engine, the oil filter captures debris particles down to a certain average size and shape. This is characterized by the filter beta ratio. The filter can also remove moisture from the oil. The heating and cooling cycles of the engine produces condensation in the crankcase air, and this condensed moisture collects in the oil and on surfaces in the crankcase such as the steel crankshaft, resulting in corrosion. With a race engine, moisture in the oil is not likely a concern, since the engine oil is replaced often.

In other types of lube system filters, such as those used in aircraft gearboxes, the oil is filtered to a very high level of cleanliness. Typically about 3 microns or less. The reason for this is that a debris particle below 3 microns in size will pass through the hydrodynamic oil film contacts in the gear tooth meshes and rolling element bearings without causing any surface damage. Automotive engine oil filters don’t filter to this level, since the filter element would need to be unacceptably large for a reasonable pressure drop.

Having an oil filter on a race engine does provide some benefit. Since race engine components tend to fail on a regular basis, the filter will remove the debris from the failed components from the oil and usually allow the engine to keep running for a while longer. The downside to having an oil filter is the additional weight and complexity.

With modern production engines, there is not much wear debris generated after an initial run-in period. The oil contaminants are mostly due to combustion blow-by, moisture and corrosion.

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