Bypass Oil Filtration

We receive many oil samples from clients who don’t understand what is required to run unusually long oil use intervals in their engines. The accumulation of wear metals, blow-by materials, and oil oxidation products in their oils is alarming. It has been our experience that one cannot simply add oil of a particular brand or base stock and expect it will be useful for an extended period of time, lubricating, cleaning, and cooling as required. Oil that becomes contaminated needs to be changed promptly. In our opinion, there are no magic oils or additives.

There are, however, auxiliary systems you can add to your engine’s lubricating system that will keep the oil clean enough to use over an extended period of time. By-pass filtration units are the most common system used for this purpose.

In-line oil filtration, which comes installed on your engine from the factory, filters oil entering the engine down to roughly 30-40 microns (millionths of a meter). This is about as finely as in-line filtration can filter, because when the oil is cold or the filter is partially plugged, a finer filter would cause too great a pressure drop, forcing open the filter by-pass valve and allowing unfiltered oil to circulate through the engine.

By-pass filtration works differently. When this type of auxiliary system is installed, some of the sump oil by-passes the in-line filter system, passing continually though a by-pass filter and then returning to the oil sump. Using this method, sump oil is constantly being cleaned any time the engine is running, and it can be filtered down to a very fine size. All you have to do to maintain the system is occasionally change the by-pass filter.

Not only do the by-pass filtration units cleanse the sump oil of blow-by and oxidation products, they also reduce wear metals and silicon accumulations, both of which are abrasive. Oil does not wear out. Its usefulness is limited by contamination. By-pass filtration removes most of the contaminants.

How long can an oil fill be run using by-pass filtration? We’ve heard claims of large (Class 8) diesels going 1,000,000 miles on the same fill of oil with no harm done to the engines. We have analyzed oils which have been in service 240,000 miles and found nothing unusual in the analysis, other than higher than average iron and lead (from steel parts and bearings), and these wear accumulations were not intolerably high.

After having run many tens of thousands of diesel engine oil samples, it is our opinion that a by-pass oil filtration system is one of the most important factors in extending oil drains. If you are interested in extended oil drains, we suggest you investigate adding this type of system to your engine.

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