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Reusable Oil Filters

Toobuilder

Toobuilder

Well Known Member
After reading several threads on the applicability of the various "automotive" filters to our aircraft, I was drawn to this product in my most recent Summit Racing catalog:


pfs-10851_w.jpg


Looks like the same kind of filter media I'm used to working with in turbine engines. Disassembly and cleaning would sure be easier than cutting/unfolding/ inspecting/disposal of the conventional filters. With this thing you just wash it out in some clean solvent and inspect the debris left behind.

Apparently, the product offered by Summit is an "offshore" product, but there is also an American offering: http://www.kandpengineering.com/technicalhighlights.shtml

I like the fact that you can get consistent micron filtering across the media, unlike paper, which is rated as an "average". As it turns out, a paper filter advertised as "10 microns" will let chunks as large as 50 microns pass. With a stainless screen, the aperture size is consistent.

Any thoughts?
 
I looked at the K&N washable filter and determined it was too easy to get junk in the clean side when cleaning. That and I've got a dozen Napa Gold 1515 filters left to use.
 
Contamination while cleaning has not been an issue in my experience.

Heck, this thing is all stainless - just throw it in the dishwasher! (Just make sure "she" is out shopping)
 
It "fits" in the sense that it is offered in the same thread and base size as the often used NAPA and K&N automotive filters.
 
got one!

I have reusable filters on my Super Cub 'Shooter' and the 'Borrowed Horse'

Stanless steel filters, seems to work fine. Both have been on my engines since new, or SMOH on Shooter. 11 oil changes on Borrowed Horse. 16 on Shooter
 
It's just a strainer, albeit better than the stock Lycoming one.
A treated cellulose media (paper) filter does a better job. Although a paper filter 'may' have voids several times larger than the micron rating, the 'in depth' nature of a paper filter means it will still trap smaller particles in line with it's rating. Besides, the whole sump full of oil goes thru the filter several times per minute. It gets filtered very well. http://en.wikipedia.org/wiki/Depth_filter
And that thing weighs more than a disposable spin on filter.
I look at those big screen units as useful in racing, and that's where you found it, in a racing supply house. Our engines have a different task, reliable continuous power. Champion & Tempest have been working on it for some time, and top quality automotive filters are similarly tasked.
 
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Paper or stainless, they are both "just strainers". The stainless version is available in 10 microns - same as the stated rating of the paper. So at worst, the stainless version is at least as good as any disposable filter. At best, it will not allow anything larger than that to pass, and it is reusable, over and over. Yes, probably heavier.
 
Stainless Filter Elements

Toobuilder said:
Paper or stainless, they are both "just strainers". The stainless version is available in 10 microns - same as the stated rating of the paper. So at worst, the stainless version is at least as good as any disposable filter. At best, it will not allow anything larger than that to pass, and it is reusable, over and over. Yes, probably heavier.
Click to expand...

The problem with stainless filters is that they can be rated in nominal as well as absolute micron ratings. The racing filter that you show is very likely a 10 micron nominal, not absolute, which means that it too may pass particles larger than 10 microns. Furthermore, stainless screen elements can "open up" larger pore sizes with age and cleaning cycles. In the aerospace industry, stainless filters are "bubble tested" when they are cleaned to verify that they continue to meet the required absolute filtration requirement when it's critical for the system in which it's used.

Skylor
 
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I have been giving thought to modifying a standard Lycoming screen to take a smaller but finer mesh filter so that it could easily be removed by taking the cap off.
 
Frantz?

I've always wondered about the Frantz Oil filter system. I met a guy once who had one on his off road truck and his 172. He absolutely swore by them. Doing some checking now, there is an STC for that filter on some older 172's. Apparently they take a cartridge that is very similar to a roll of toilet paper.

Seems like it would be a mess to use, but he claimed that that his oil in the truck and the plane was almost clean and clear when it was time to change.
 
skylor said:
The problem with stainless filters is that they can be rated in nominal as well as absolute micron ratings. The racing filter that you show is very likely a 10 micron nominal, not absolute, which means that it too may pass particles larger than 10 microns...
Click to expand...

That conflicts with the information on one of the manufacturers sites, but it may be the case. But if so, it is no worse than the throw away cardboard element, right? Which is fine, as I was not looking for a "superior" form of filter anyway - just one that can be serviced and inspected easier. After all, these engines ran for decades with only the screen. The spin on filter is a fairly recent development.

And to top it all off, it looks like a version of this is offered from Spruce as a FAA/PMA part for certified aircraft. It's 300 bucks though, and appears suspiciously like the K&P unit described in my initial post. It appears the concept is sound.
 
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There is a lot more

to oil filters than the micron rating. The screen can do the job of hot oil absolute particle capture just fine. The recip engines produce a LOT more volume of particles than a turbine lube system. All that rubbing and sliding of parts produce more particles. Also, there is some that comes off the cylinder walls due to contact with debris in the air. Yes most is captured in a good air filter, but not all. We typically don't have good air filters.

While a screen, or essentially orifice(s), filter can do the job if filtering, the capacity is the key in the papers. There is a lot of detail about distribution of particle sizes and all that, but the paper elements will hold many X the volume of material before the pressure drop becomes unacceptable (and bypasses on cold start). By example, just put in a 10 micron rated filter and see how long it takes for it to reach the delta-p limit, it will be very quick.

Is better lube oil filtration better for wear and engine life? Yes, absolutely! But, it would take a lot of development to get that. Pressure drop, capacity, cold starting, bypass, etc. The best filtration is to use centrifugal separators in oil bypass, but that is too heavy for our application. (http://glaciercentrifuge.com)

So, in my (decades of engine development) opinion, this is not a bad option, but it is not the best option for oil filtration. I am sticking with standard filters.

If I really wanted cleaner oil, I would recirculate the oil on the ground (kidney loop) the engine oil on the ground through a 5 micron hydraulic filter for a few hours with a continuous particle counter monitor, that is how the industry does it for transmissions and axles for large equipment that need to go 40,000 hours before overhaul.

Reference: Donaldson develops their own filter papers and they are outstanding filtration people in theory and practice, here is a taste. http://www.donaldson.com/en/ih/support/datalibrary/033986.pdf

(yes I have too much time on my hands, waiting on a Spruce shipment :D )
 
Just thinking out loud here, but all spin on filters work the same way, regardless of media type. Paper is the most popular because it works fine as a one time use and is cost effective. A manufacturer could replace that paper with stainless mesh and achieve the same level of protection, but of course could not compete at the price point. So all else being equal, there is nothing superior about paper that drives the popularity. It's all about cost.

Is there any evidence that paper/cardboard elements deliver superior performance to the appropriate stainless mesh/cloth elements? Just talking about the media here, not drain back valves, burst pressure, etc.
 
Here's another thought: my 2005 Mazda 3 (and maybe my new 2012 Mazda3 too, but I haven't checked yet) has a replaceable cartridge filter that gets changed every 8000km (!!!). In form, it's not much different than the re-usable filter shown above, but has a plastic body and a paper filter cartridge.

Why not use something similar on aircraft, a replaceable filter element but reusable housing?
 
Snowflake said:
Why not use something similar on aircraft, a replaceable filter element but reusable housing?
Click to expand...

Back before the advent of disposable spin-on filters Champion made a filter with a replaceable element. I have an old O-320 that has one. If you look in the old parts catalogs there are exploded diagrams of these filters.
 
Hi Michael

I am pleased to see someone challenging a way of operating. I too have challenged things in a different career and dinasours said "well we've always done it that way".

So if I challenge something and someone gives me a valid explanation then I go with it. Watching the thread with interest and in the meantime I'll stick with my K&N paper filter (the Champion is too wide and chafes on my vac pad inverted oil pick up hose).
 
I'm really in favor of a replaceable filter like the K&P unit. On the face of it, a bit more environment friendly and it does look cool. Problem is for the $200. plus shipping I can buy 30 spin on filters. At my rate of consumption, I will break even when I am 81. Also, have you bought any solvent recently?

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
As far as price point goes, Spruce is selling them for $300; K&P is apparently $200; and Summit sels their version for $95. I'm guessing the version from Summit is less robust than the other two, but likely will still meet our relatively modest requirements. On price alone, it's tough to justify. However, I don't get real excited about cutting open filters and unwinding a yard of cardboard looking for metal.
 
How about automotive?

My BMW540 has a remote oil filter with an aluminum housing and replaceable element. When the cap comes off it triggers a drain that allows all the oil surrounding the element to drain to sump. Nice large, braided oil hoses and mounted to the chassis at the fender wall. You can keep the excellent filtration characteristics of a paper element, good source of high quality filter elements, easy filter cutting for inspection and proven pressure and pulsation tolerance? It is all alloy, so it is light. Oil sample analysis each oil change shows consistent particle count for last 120k miles. It mounts so the filter comes out the top for no mess during replacement.

My car is an E39, but here is one for an E38 (V8) that may be in our price range.

http://www.ebay.com/itm/BMW-OEM-E38...Parts_Accessories&vxp=mtr&hash=item337edf98b7

A line drawing of the assembly for the E39 540 http://www.realoem.com/bmw/showparts.do?model=DN53&mospid=47588&btnr=11_1591&hg=11&fg=30

How's that for a dinosaur?
 
BillL said:
My BMW540 has a remote oil filter with an aluminum housing and replaceable element...
Click to expand...

That's pretty neat Bill. That would be an interesting option for someone needing/wanting a remote unit. I would guess that there is a drop in stainless element somewhere as well.
 
My VW diesel's oil filter is almost identical to the BMW unit except it is mounted directly to the block. Its easy to change however the price of the elements are 2X what I pay for Napa Gold 1515's that I use on a Lycoming. I really don't find it any more convenient than a spin on other than not having a can to cut to inspect it. In fact its sort of a pain because you have to have a container to drop the element in since its dripping with oil.

Hard to beat using a $6.79 automotive spin on filter.
 
The thing is, a screen element, if it were really a screen which I don't think this one is, has a discreet number of holes. A paper element works by not only "screening", but particles are attracted to and stick to the paper. As a result the filtration is specified as an efficiency and the dirt capacity is very high. You will notice in the K&P filtration data that ther is no scale on the plot, which means it is nothing more than marketing BS (I mean info), even though they have it in their "technical" section. With what I know and have experienced with filters, both professionally and personally, I use paper, but quality paper filters

All that said, the bottom line is that engines don't typically fail due to inadequate oil filtration. They need overhauls for other reasons. That means that these stainless filters are probably just fine in the application and they allow for a very profitable aftermarket business opportunity ;)

IMHO

Tim
 
Cleanable oil filters

Challenger aviation supplys cleanable/reusable oil filters that replace most aviation spin on filters. They filter quite well but they are time consuming to clean and the little magnets are really a pain as they must be removed and mechanicly cleaned as solvent bath & ultrasonic wont remove fine iron particals. I prefer the Tempest disposable filters with intragal magnet from AERO. I can cut down, inspect, and replace these in far less time than I can properly clean the reusable units. Russ
 
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rocketbob said:
My VW diesel's oil filter is almost identical to the BMW unit except it is mounted directly to the block. Its easy to change however the price of the elements are 2X what I pay for Napa Gold 1515's that I use on a Lycoming. I really don't find it any more convenient than a spin on other than not having a can to cut to inspect it. In fact its sort of a pain because you have to have a container to drop the element in since its dripping with oil.

Hard to beat using a $6.79 automotive spin on filter.
Click to expand...
Rocketbob, What is the engine that you use a Napa filter on?
Dave
 
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