Aviation Oil Filters Tested ~ 40% efficiency at 20 microns?

[2.7ecoboostFordBronco]

Vans Air Force Oil Filter Test

I didn’t find a thread discussing this here in a search, so feel free to link to it if I missed it. The testing was mostly geared toward assessing the effectiveness of the reusable challenger/k&p filters compared to disposable filters, in part due to champion/tempest shortages during 2020-2023.

I am posting it because I was curious about the thoughts of bitog’s oil filter experts on the seemingly low efficiency of the tempest and champion filters particularly. These are the mainstay filters of the piston powered airplane fleet. I was disappointed to see how low their efficiency is under 30 microns, but maybe that is an unfounded concern, or an imaginary problem on my part. They also cost about $50/ea.

On experimental, airplanes, the owner is free to choose any filter. On certified airplanes it seems to be a legal gray area. Some people on the linked thread were advocating to use the Wix filter instead of the aviation-marketed Champ or Tempest. Given the M&H QC issues I’ve seen discussed here I don’t know if I would risk that.

My questions are,

Is the lack of safety wire attachment points on the non-aviation filters a major concern given the relatively high vibration environment of an airplane? Maybe something like a K&N HP2004 with a nut that has a safety wire hole would be a good compromise for better efficiency? Then again, I’ve read of those nuts failing and causing oil starvation.

Lycoming and Continental, the airplane engine maker duopoly, specify 11-12 psi minimum bypass pressure, would auto filters bypass too soon? With that said apparently the champion aviation filters still bypass at 8-10, or at least they did the last I saw them tested in the mid 00’s.

How would the Lead in aviation 100LL load up a filter designed for car applications, like this Wix? As I understand it, dispersing/holding lead is a major function of piston airplane motor oil. I really don’t know how much of this an oil filter in an engine running leaded fuel cleans out. My oil analysis usually shows about 3000 ppm lead.

 

[ZeeOSix]

I didn’t find a thread discussing this here in a search, so feel free to link to it if I missed it. It is mostly geared toward assessing the effectiveness of the reusable challenger/k&p filters.

Based on the efficiency info in the posted table, I don't think I'd call them "filters". The other 3 aren't very efficient, Wix being the best of those three.

Are aircraft filters required to be safety wired?

 

[ZeeOSix]

On experimental, airplanes, the owner is free to choose any filter. On certified airplanes it seems to be a legal gray area. Some people on the linked thread were advocating to use the Wix filter instead of the aviation-marketed Champ or Tempest. Given the M&H QC issues I’ve seen discussed here I don’t know if I would risk that.

There are other filters on the market to choose from that will cross-reference to the Wix 51515.

 

[2.7ecoboostFordBronco]

Based on the efficiency info in the posted table, I don't think I'd call them "filters". The other 3 aren't very efficient, Wix being the best of those three.

Are aircraft filters required to be safety wired?

On an experimental there is no requirement. On a certified (Cessna, piper, etc) I think it’s another gray area. I’ve seen it discussed to use a hose clamp around an auto oil filter and safety wire to that.

 

[ZeeOSix]

On an experimental there is no requirement. On a certified (Cessna, piper, etc) I think it’s another gray area. I’ve seen it discussed to use a hose clamp around an auto oil filter and safety wire to that.

Yes, like below would work well. If I was flying or in an airplane, I'd definitely want the filter secured. Put the hose clamp close to the base where the can is stiffer.

 

[2.7ecoboostFordBronco]

Yes, like below would work well. If I was flying or in an airplane, I'd definitely want the filter secured. Put the hose clamp close to the base where the can is stiffer.

View attachment 268993

Thanks. I will probably keep using the Champion 48108-1 aviation oil filters for now while I look into this more. The 43% @ 20 micron rating just seemed really lousy for a $50 filter and I’m wondering if there’s something I’m missing. Then again many of these types of engines still use oil screens instead of filters, but with specified oil change intervals halved.

 

[Propflux01]

Thanks. I will probably keep using the Champion 48108-1 aviation oil filters for now while I look into this more. The 43% @ 20 micron rating just seemed really lousy for a $50 filter and I’m wondering if there’s something I’m missing. Then again many of these types of engines still use oil screens instead of filters, but with specified oil change intervals halved.

The engine will survive to its Time of Overhaul. (Think like old VW air-cooled, but with some filtration). Engine needs oil more than filter when at 7000 Feet. As for the $50, well, it shows a picture of an airplane on the box.

 

[dnewton3]

Wix reported at 7% at 5um and 78% at 20um is a far cry for their typical advertised "2/20=6/20" beta ... for whatever that's worth. Given that the filter test standard used is akin to the typical ISO protocol we're all familiar with, this begs the question of just how far off any one particular filter model (or even brand) these really are ?

 

[Cujet]

I suppose the one good thing about the Champion filter is quality construction. You know what you are getting. They are very unlikely to fail. I cut them apart at every oil change, always the same. Unfortunately, the price is now in the insane range.

I found this sloppy picture on the web, you can see the metal parts, bypass valve and spring, and rubber anti drainback valve.

 

[Cujet]

Items that stand out to me with regard to Aviation Oil Filters.

Typically conventional light piston aircraft use 50 viscosity oil, with some users choosing 15W-50 or 20W-50. Filter flow rate must be adequate to deal with this viscosity during run up, before oil is fully warm, without bypassing.

Lycoming/Cessna often allows an engine run up when oil temperature reaches 100ºF. But there are operators (flight schools with ops specs and so on) who require 120ºF oil temp before the throttle is pushed to the 1700/1800RPM point. My plane does not indicate if oil is over 100ºF, gauge is green band and a red line. Experience says the needle will be below the green band if it is less than 90º outside.

Also, the Champion filter has a nut for torquing it down, not just to remove it. The filter seal is failure/leak proof on Champion filters because of how it is captured, how much it compresses and the material chosen. It will work, hot or cold. The same cannot be said for non standard filters in aviation use. Aircraft use will find flaws that don't exist elsewhere.

The Challenger oil filter and it's aftermarket equivalent is a screen and while not a great filter, it is convenient and cheap. Unfortunately, too many have experienced in flight o-ring failure and leakage. I won't use one. Stainless filter elements can be epic good when designed and made properly, this one is not good enough on multiple fronts.

 

[wings&wheels]

I would guess that the low efficiency is intentional due to the suspended lead and amount of carbon and other contaminants carried by the oil vs. in a typical auto engine. This is one area that I would not choose to economize on via unapproved parts.

 

[2.7ecoboostFordBronco]

Items that stand out to me with regard to Aviation Oil Filters.

Typically conventional light piston aircraft use 50 viscosity oil, with some users choosing 15W-50 or 20W-50. Filter flow rate must be adequate to deal with this viscosity during run up, before oil is fully warm, without bypassing.

Lycoming/Cessna often allows an engine run up when oil temperature reaches 100ºF. But there are operators (flight schools with ops specs and so on) who require 120ºF oil temp before the throttle is pushed to the 1700/1800RPM point. My plane does not indicate if oil is over 100ºF, gauge is green band and a red line. Experience says the needle will be below the green band if it is less than 90º outside.

Also, the Champion filter has a nut for torquing it down, not just to remove it. The filter seal is failure/leak proof on Champion filters because of how it is captured, how much it compresses and the material chosen. It will work, hot or cold. The same cannot be said for non standard filters in aviation use. Aircraft use will find flaws that don't exist elsewhere.

The Challenger oil filter and it's aftermarket equivalent is a screen and while not a great filter, it is convenient and cheap. Unfortunately, too many have experienced in flight o-ring failure and leakage. I won't use one. Stainless filter elements can be epic good when designed and made properly, this one is not good enough on multiple fronts.

Thanks! Given all that, interesting that aviation consumer said the champion aviation filters still bypassed at 8-10 psi when tested. Another argument for preheat, I guess.

I’ve never seen a minimum oil temp for runup written anywhere for the airplanes I’ve flown, good to know that 100F is about what lyc/cont look for. I hate to say though, there are some days below 0F where it just isn’t going to get to 100 warming up at ~1100 rpm even if I sit there for an hour. My current lyc IO-360 powered plane’s AFM just says “The engine is warm enough when it idles at around 600 RPM and accelerates smoothly. Ensure the oil pressure is within the green arc on the gauge.”

 

[ZeeOSix]

Vans Air Force Oil Filter Test

View attachment 268987

I didn't go digging much into the chat board linked above, but wondering if they also did some ISO 4548 flow vs dP testing with "cold" (~500 cSt) and "hot" (~15 cSt) oil.