The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly. I know that some vehicles have in-engine bypass valves (I have an Impala with one) and therefore the filters don't require a bypass valve, but many more vehicles specify a bypass in the filter. The ones I have examined appear to be rather poor at sealing, and often just sit on one of the filter endplates with metal-to metal contact--no gasket or seal of any sort between the valve assembly and the endplate. On many filters, notably say Fram TGs, the bypass valve assembly just sits in a cutout in the cardboard endplate. These designs must leak a fair bit of oil in operation, and of course they also open up at times during cold starts or hard acceleration. It seems that vehicle and filter engineers are not too concerned with "dirty oil" bypassing the filtration medium.
Are "full-flow" filters really full flow?
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The filters have an efficiency printed right on the box for you.
Yes, but how is that tested? Is it just the filter element, or is it the actual commercially available filter attached to some device? It's hard to believe the metal-to-metal contact between the bypass valve and the filter endplate is a good seal--not that much pressure on the joint either. Even the valves don't appear to seal that well on some filters.
The filters have an efficiency printed right on the box for you.
Yes, but how is that tested? Is it just the filter element, or is it the actual commercially available filter attached to some device? It's hard to believe the metal-to-metal contact between the bypass valve and the filter endplate is a good seal--not that much pressure on the joint either. Even the valves don't appear to seal that well on some filters.
Purolators are full-flow
Originally Posted By: AuthorEditor
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly. I know that some vehicles have in-engine bypass valves (I have an Impala with one) and therefore the filters don't require a bypass valve, but many more vehicles specify a bypass in the filter. The ones I have examined appear to be rather poor at sealing, and often just sit on one of the filter endplates with metal-to metal contact--no gasket or seal of any sort between the valve assembly and the endplate. On many filters, notably say Fram TGs, the bypass valve assembly just sits in a cutout in the cardboard endplate. These designs must leak a fair bit of oil in operation, and of course they also open up at times during cold starts or hard acceleration. It seems that vehicle and filter engineers are not too concerned with "dirty oil" bypassing the filtration medium.
Hardly any oil bypasses the media, even in the mediocre designs you mentioned. Good stuff has better sealing than that.
In the second place, just how much "dirt" do you think an engine adds to its oil on a single pass from the sump through the engine and back to the sump? The answer is "hardly any, unless its in the act of tearing itself apart at that moment." The oil that doesn't get filtered when the filter DOES go into "bypass"mode is only infinitesimally "dirtier" than it was the last time it got filtered.
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly. I know that some vehicles have in-engine bypass valves (I have an Impala with one) and therefore the filters don't require a bypass valve, but many more vehicles specify a bypass in the filter. The ones I have examined appear to be rather poor at sealing, and often just sit on one of the filter endplates with metal-to metal contact--no gasket or seal of any sort between the valve assembly and the endplate. On many filters, notably say Fram TGs, the bypass valve assembly just sits in a cutout in the cardboard endplate. These designs must leak a fair bit of oil in operation, and of course they also open up at times during cold starts or hard acceleration. It seems that vehicle and filter engineers are not too concerned with "dirty oil" bypassing the filtration medium.
Hardly any oil bypasses the media, even in the mediocre designs you mentioned. Good stuff has better sealing than that.
In the second place, just how much "dirt" do you think an engine adds to its oil on a single pass from the sump through the engine and back to the sump? The answer is "hardly any, unless its in the act of tearing itself apart at that moment." The oil that doesn't get filtered when the filter DOES go into "bypass"mode is only infinitesimally "dirtier" than it was the last time it got filtered.
I'm not arguing that it is bad (or good), just pointing out that some of the oil bypasses the filtration medium at least some of the time, and maybe more of the time than we imagine.
Originally Posted By: slacktide_bitog
Purolators are full-flow
Purolators are full-flow
Originally Posted By: slacktide_bitog
Purolators are full-flow
As is the OCOD when the cardboard shreds.
Purolators are full-flow
As is the OCOD when the cardboard shreds.
JTK
$100 Site Donor 2025
Downstream of most engine oil pumps is a pressure relief, then the oil filter, which has a bypass or pressure relief, so not all oil is going through the media at all times.
and the arguments start. 
)
)The tough guard actually has a better seal against the bypass valve than metal to metal. There is some minor leakage with metal to metal which is why the Ultra uses the gasket instead of metal to metal, but the efficiency tells you about leakage which is why it's important to know the ISO 4548-12 results.
Yes, all the oil that goes in, goes out. The engine relief valve is just there for catastrophic events to protect the system, not opening normally. The spring inside the filter holds everything tight, even metal to metal. If any oil passes between reasonably flat and smooth metal to metal seals held together under pressure, it would be "filtered." The Fram seals are fine, the Ultra uses an extra gasket on the bypass valve, a nice touch of quality. That's IMO.
Originally Posted By: AuthorEditor
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly.
I don't think there really is much "leakage" around the bypass valves or around the end caps center tubes. Reason I say that is because IF they did leak a lot, the efficiency tests would not come out as high as they do on some of these filters (ie, some 99% @ 20 microns).
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly.
I don't think there really is much "leakage" around the bypass valves or around the end caps center tubes. Reason I say that is because IF they did leak a lot, the efficiency tests would not come out as high as they do on some of these filters (ie, some 99% @ 20 microns).
Originally Posted By: AuthorEditor
Quote:
The filters have an efficiency printed right on the box for you.
Yes, but how is that tested? Is it just the filter element, or is it the actual commercially available filter attached to some device? It's hard to believe the metal-to-metal contact between the bypass valve and the filter endplate is a good seal--not that much pressure on the joint either. Even the valves don't appear to seal that well on some filters.
The WHOLE filter assembly is tested in the ISO efficiency test. The filter is screwed onto the test machine just like it's screwed onto an engine.
Quote:
The filters have an efficiency printed right on the box for you.
Yes, but how is that tested? Is it just the filter element, or is it the actual commercially available filter attached to some device? It's hard to believe the metal-to-metal contact between the bypass valve and the filter endplate is a good seal--not that much pressure on the joint either. Even the valves don't appear to seal that well on some filters.
The WHOLE filter assembly is tested in the ISO efficiency test. The filter is screwed onto the test machine just like it's screwed onto an engine.
Originally Posted By: JTK
Downstream of most engine oil pumps is a pressure relief, then the oil filter, which has a bypass or pressure relief, so not all oil is going through the media at all times.
If the filter's bypass stays completely closed (and the media isn't torn), then 100% of the oil that goes into the engine is filtered.
Downstream of most engine oil pumps is a pressure relief, then the oil filter, which has a bypass or pressure relief, so not all oil is going through the media at all times.
If the filter's bypass stays completely closed (and the media isn't torn), then 100% of the oil that goes into the engine is filtered.
Originally Posted By: ZeeOSix
Originally Posted By: AuthorEditor
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly.
I don't think there really is much "leakage" around the bypass valves or around the end caps center tubes. Reason I say that is because IF they did leak a lot, the efficiency tests would not come out as high as they do on some of these filters (ie, some 99% @ 20 microns).
Even more if you look at the upcoming rating of the Ultra as 99.9% it must have a very very very good seal....
Originally Posted By: AuthorEditor
The typical spin-on oil filters many of our vehicles use are supposedly "full-flow" designs, meaning all the engine oil passes through the filter. However, the way many filters are designed it appears very likely that some oil leakage around the filter element occurs fairly often if not constantly.
I don't think there really is much "leakage" around the bypass valves or around the end caps center tubes. Reason I say that is because IF they did leak a lot, the efficiency tests would not come out as high as they do on some of these filters (ie, some 99% @ 20 microns).
Even more if you look at the upcoming rating of the Ultra as 99.9% it must have a very very very good seal....
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