ISX and Bypass Oil Filter Systems

[Rawze]

I came across this today from cummins. it talks about why they do not recommend extended oil changes...

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Cummins does not recommend that oil analysis be used to determine maintenance intervals. Oil analysis only permits maintenance intervals to be estimated. Engines must be operated at the estimated interval for 800,000 to 1,100,000 km [500,000 to 700,00 mi] or 10,000 to 15,000 hours to determine if the estimated maintenance interval based on an oil analysis was correct.

If the interval is estimated correctly, the engine will remain in an acceptable condition for its operating environment. If an extended maintenance interval is guessed incorrectly, up to 50 percent of the potential engine life to rebuild can be sacrificed for the longer maintenance interval. For example; an engine with 3220 km [2,000 mi] per quart oil consumption during the first 8050 km [5,000 mi] of an interval can consume oil at 805 km [500 mi] per quart with 32,000 km [20,000 mi] on the oil.

Slow accumulation of wear metals can reflect increased oil consumption, not low wear rates because of dilution by more new oil. Low wear rates on engines operating toward the end of the maintenance interval are required to prevent a large loss in engine life to overhaul. Many used oil testing procedures have been developed from quality control tests for new engine oil. In new engine oil, these tests reflect chemically active additives in the oil.

They make sure that each time the oil is blended it contains the correct amount of additives. When these test procedures are applied to contaminated and deteriorated used oil, the data will not be meaningful. Additives take a different chemical form in used oil. Commercially available oil testing techniques do not measure depletion of all the chemical additives in the oil, or determine when these additives stop protecting engine parts from wear and deposits. Low wear metal levels in used oil samples can reflect high oil consumption rates and dilution with new oil added to replace that consumed. Low wear metal levels in used oil samples can also reflect additional contamination and wear debris. Engine oil operated beyond this saturation point often drops contamination and wear debris out as sludge. This results in declining wear metal levels at increasing kilometers [miles] or hours on the oil.

This does not mean that wear rates are decreasing and oil condition is improving. It means that oil analysis becomes meaningless after the engine oil is excessively contaminated.

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It is part of this document...

http://rawze.com/publicfiles/ISX/Informa...810340.pdf