Engine Wear Study - Included Oil Filtration

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So many times we've heard people say that the oil filter efficiency doesn't really do anything to help reduce engine wear.

See Section 8 Oil filtration in the study linked below. There is other talk in the study about air and oil filtration, the effect on oil cleanliness and the correlation to engine wear, so the whole study is well worth reading IMO.

The only thing that's not clarified is what they really mean when they say the "oil filter rating" is 10u or 20u etc. I'd have to assume it means the "absolute efficiency" rating (Ie, basically meaning @98%).

Of course, as we all know, the air filter efficiency has much more effect on engine wear, but the paper does show that adding high oil filtering efficiency to keep the oil cleaner can eek out a measurable amount of engine wear reduction. Looking at Figure 18, it looks like an oil filter rated at 98% @ 20u would reduce ring wear by nearly 30% over a filter rated at 98% @ 50u. Efficiency would have to get down to around 98% @ 10u or better to really make wear drop off quickly. Hence, the need for bypass filtering systems. But keep in mind that any filter that's rated 98% @ 20u is also filtering out a pretty fair amount of particles below 20u (typically around 60% to 80% @ 5u).

Bottom line is cleaner oil is always better than dirtier oil when it comes to reducing engine wear, regardless of how you get there.

Pretty good study IMO. You can download the entire paper in PDF in the upper RH corner ("Download full-text" button).
https://www.researchgate.net/public...and_filtration_on_automobile_engine_wear
 
That had more relevance in 1991 when it was written, they are talking about the effects of sand dust inside the engine.
Years ago crankcase ventilation was poorly filtered if at all on most engines. At best they had a small fiber filter inside the filter housing that was pre air filter at worst the hose was gone and just took air into the crankcase through the valve cover fitting.

This has not been done since the early 90's, today the crankcase breathes post air filter and the PCV system is very tight and very few particles get into the crankcase, no more than the engine cylinders themselves this translates to the the more efficient the air filter the less engine will result.
Oil filter efficiency is much less relevant today at preventing engine wear than back in those days, diesels are different and definitely do benefit from better oil filtration.

This is old type PCV breather system, it didn't filter much of anything as it was before the main air filter.

[Linked Image]


Inside the housing there was small filter if you can call it that.

[Linked Image]


A lot of particles got into the crankcase with these systems so a more efficient oil filter certainly made a big difference.

Today this type of system is common, the smaller tube after the air filter element is the source for crankcase ventilation.

[Linked Image]
 
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I glanced through it, and found it was interesting reading for sure. Seems to apply to aircraft quite significantly. Aircraft owners are cautioned not to fly in the ash plume of volcano's. While this seems self evident, it's not. As quite often the ash plume can be many hundreds of miles away from the source, and invisible.

In any case, both gas turbine and reciprocating aircraft engines exhibit extremely rapid wear when ingesting ash.

While I did not see timing chains included in that particular testing, it's clear that timing chains are very sensitive to wear causing particulates.

I'd guess that there is still a place for sub-micron oil filtration.
 
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Trav, I think you just visually proved the opposite of your written claim, didn't you? According to your pictures, in the past PCV vapors were pulled into the intake through the main air filter (as your picture of that old American V-8 shows). Thus, the air filter worked as well to clean up the PCV vapors as it did cleaning general intake air.

Today, per your lower picture, PCV vapors are generally unfiltered. Thus, the main air filter has no impact on PCV vapors. This would also help explain why DI intake tract carbon build-up can be such a problem; no PCV vapor filtration.

Based on the pictures, then, oil filter performance is much _more_ relevant today than it was decades ago.
 
I had a Ford V8 I ran a catch can inline between PCV and Throttle Body. But I capped the fresh air intake for the crankcase. This caused the crankcase to run under vacuum as long as the intake was in vacuum, usually around 5"Hg. Worked great but there were some weird pumping noises when idling.
 
I haven't seen anyone say oil filter efficiency doesn't reduce wear. Efficiency is a word in itself it doesn't mean the SAE test only. Here is a recent real world test taking full flow filtered oil and filtering it again using a higher efficiency filter. Nicely improving the particles in the oil.

https://www.frantzfilters.com/science/

Good to see they mention hardness of particles, mineral particle degradation, and all that.
 
Originally Posted by bulwnkl
Trav, I think you just visually proved the opposite of your written claim, didn't you? According to your pictures, in the past PCV vapors were pulled into the intake through the main air filter (as your picture of that old American V-8 shows). Thus, the air filter worked as well to clean up the PCV vapors as it did cleaning general intake air.

Today, per your lower picture, PCV vapors are generally unfiltered. Thus, the main air filter has no impact on PCV vapors. This would also help explain why DI intake tract carbon build-up can be such a problem; no PCV vapor filtration.

Based on the pictures, then, oil filter performance is much _more_ relevant today than it was decades ago.


No you are interpreting the system backwards. The PCV (most common ones) use a vacuum to draw crankcase vapors into the combustion chamber via the intake or plenum.
On the other side of that system it needs fresh air coming in or it would suck every seal in the engine in. This fresh air is what needs to be filtered.
A hose connected after the air filter provides well filtered air for the crankcase the old system does not, the small filter mounted inside the air filter housing is pre filter and does not do a very effective job.

No PCV vapors are filtered in either system.
 
Originally Posted by Trav


No you are interpreting the system backwards. The PCV (most common ones) use a vacuum to draw crankcase vapors into the combustion chamber via the intake or plenum.
On the other side of that system it needs fresh air coming in or it would suck every seal in the engine in. This fresh air is what needs to be filtered.
A hose connected after the air filter provides well filtered air for the crankcase the old system does not, the small filter mounted inside the air filter housing is pre filter and does not do a very effective job.


Okay, I certainly agree that the PCV intake should be filtered.

All the light and medium duty vehicles I owned or operated back to the mid-70s models had filters on the PCV intake. Were those lower-efficiency than the main air filters at the time?
 
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It was true in 1991 with the data they had. Since then technology has improved, along with filtration. Let's search for the newest research and models and not get stuck back in 1991.
 
Oh yes, they were barely able to filter rocks. They allowed a lot of particles in the crankcase which cause a lot of wear, today we don't see too many worn out oil pumps due to scoring in the housing. Back then it was common especially the ones that used aluminum housing like the Buick V8, pump housing wear was mostly due to particles in the oil that hit the pump before the oil filter.
 
Pretty much all engines that went fuel injection got away from an "open breather" for the PVC fresh air intake because it needed metered air for the FI ECU control. My 1985 Camaro with a port fuel injected 305 didn't have a "breather" on the valve cover.
 
Originally Posted by Trav
That had more relevance in 1991 when it was written, they are talking about the effects of sand dust inside the engine.
Years ago crankcase ventilation was poorly filtered if at all on most engines. At best they had a small fiber filter inside the filter housing that was pre air filter at worst the hose was gone and just took air into the crankcase through the valve cover fitting.

This has not been done since the early 90's, today the crankcase breathes post air filter and the PCV system is very tight and very few particles get into the crankcase, no more than the engine cylinders themselves this translates to the the more efficient the air filter the less engine will result.
Oil filter efficiency is much less relevant today at preventing engine wear than back in those days, diesels are different and definitely do benefit from better oil filtration.

This is old type PCV breather system, it didn't filter much of anything as it was before the main air filter.

[Linked Image]


Inside the housing there was small filter if you can call it that.

[Linked Image]


A lot of particles got into the crankcase with these systems so a more efficient oil filter certainly made a big difference.

Today this type of system is common, the smaller tube after the air filter element is the source for crankcase ventilation.

[Linked Image]






My 83 Caprice has the same system as in your picture of the Buick v8, my Oldsmobile has the aftermarket round chrome breather that goes directly into the valve cover to filter crankcase. Is this any better than the factory setup inside the air cleaner?
 
Originally Posted by caprice_2nv


My 83 Caprice has the same system as in your picture of the Buick v8, my Oldsmobile has the aftermarket round chrome breather that goes directly into the valve cover to filter crankcase. Is this any better than the factory setup inside the air cleaner?


You can replace the breather cap with a sealed one that takes a hose and put a good filter on the end. As long as there is no blowby then that would not make a mess.
 
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