Dave Newton made a great post on another thread that I believe is very pertinent to this one. With all the consternation about Wix's combo bypass, read this.
Originally Posted By: dnewton3
You know, so many folks make the wrong presumption about why the filter bypass exists in the first place.
Generally, the bypass valve is not there to protect the engine; there is way more flow (volume and velocity of oil) supplied by the pump than the engine needs. Any excess "flow" is burped off at the pump relief. The high pressure at the cold start cycle cannot be interpreted to mean that the engine is starving for oil. It is only an indication that pressure in the system is building due to OVERALL SYSTEM resistance, not just at the filter. Jim's data shows that the filter bypass will open under very limited circumstances, but when it does, that should NOT be interpreted to mean that the engine was starving for oil. It ONLY means the media was being protected. Once relief starts (within fractions of a second) the output from the filter is balanced again to system pressure. The bypass valve in the filter is to protect the media from being blown out (for a lack of a better term). It does nothing to save the engine from destruction. The pump relief operates on a principle of delta P between oil circuits and atmospheric pressure (typical vented sump system). But the filter operates on dP across the media. Don't confuse the two, or their intended functions.
I will also note that the size of the opening for the bypass valve in the filter is likely large enough to pass enough volume and velocity that the engine would not starve for oil in the critical pathways, should the media ever blind off to a point of total obstruction (think total neglect). The only time the media is at risk is when the delta P across the media is high enough, long enough, for the media to succumb to destruction. That is practically never, folks. In short, even fully blocked media should not keep oil from reaching the engine. It would be undesirable because it's unfiltered, but the engine surely would not starve for oil.
The only time the engine is at pressure and flow risk is when the pump isn't performing to a minimum requirement, or the relief valve is stuck open.
As for filter bypass events, I've said this before and I'll say it again. Results trump theory every time.
One of two conditions MUST exist; there are no other alternatives.
1) filter bypass events are frequent
2) filter bypass events are infrequent
Either way, where is the data to show that one theory results in heavy wear trending versus the alternative? We have some decent data from Jim to show that the truth is predominant in condition 2. But does it really matter overall? Will a larger filter (all other conditions being equal) result in any tangible difference in wear? Wear being defined as statistically significant that can be counted upon as proof in a UOA, or in teardown analysis ... I see none. Feel free to point it out if you have access to it, because it would be of profound interest to me. To be truly viable data, we'd need a large series of sample UOAs in both conditions. Read my article on UOA normalcy to understand the basics.
The ONLY time I could see a larger fitler being of use is if the following operational conditions happened:
1) the "normal" filter was used so long that it totally blinded off the media, and the filter was in perpetual bypass (a larger filter would not prevent this, but it could defer it in time)
2) the continual contamination accumulation was great enough that the oil add pack was eventually overwhelmed and could not contain the harmful particulate in a manner to prevent wear escalation; in essence the particulate load would overcome the additives and attack the barrier in a manner sufficient to alter wear trending
Let us not forget SAE 2007-01-4133 that shows longer O/FCIs indicate that wear trends DOWN as the OCI gets longer (at least out to 15k miles). There most certainly is a point where wear would reverse its trend, and start up. But we have no DATA, no FACTS, to show when that would be. AND, that study did not utilize different filter sizes; that would be an entirely different study all together. The main contolling entity in wear control is NOT the filter; it is the tribochemical barrier that is developed after OCI. Would it be your supposition that a larger filter would have made for even less wear in this study? The wear was down by a factor of 10 after just a few thousand miles for goodness sake! The wear was so negligible that it was almost non-existent! Just how much "better" do any of you think a "bigger" filter would make it????? The only way to know how these would react independently would be to run several DOE tasks where you manipulated the OCI and FCI, only AFTER the wear trends were affected. You would have to run control groups and study groups. You'd have to seek to affect the wear by manipulating the filter media only AFTER the wear trended up in "normal" circumstances. How many of you have tried this? How many of you have read about this? To this date, I have NEVER seen any such study.
My closing points are these:
- there is reasonble data to show that bypass events are infrequent (Jim's data and his affirmation of information from engineers in the filter industry)
- there is reasonable data to show that bypass infrequent events are harmless (thousands of UOAs here and elsewhere)
- there is reason to conclude that filters do not directly affect lube flow to a point of equipment starvation with components in good condition (pinciple understanding of hydraulic systems)
- there is reasonable data to show that OEM filters (even at 15k miles) offer fine procection, complimentary to the tribochemical barrier (SAE study)
- there is no data to show that larger filters would alter these conditions, at least in a practical sense where any BITOGGer would ever tread
To coin a phrase ...
The only thing a Bittoger has to fear is filter fear itself.
I had great results with the combo valved Silver so far. When I cut it, combined with my results if it looks good there is no reason to think the bypass wasn't working. If the media appears to be subjected to signs of excessive pressure or torn, I'd say I'd be done with them.
Surely you would think Wix engineers would have thought of cold starts, long OCI's and thick oil when they designed and tested the combo valve.
I don't like the combo valve on the ecore because 1) it's an ecore and 2) when I tested one it didn't work right for me. The Wix combo valve is a different animal.
