Filter change interval

[MisterBen]

I have a spin-on filter kit I recently installed on my transmission line (which some of you may have seen, there are pics in the transmission section).

What would be a good interval to changing the filter on there? I don't want the filter to fall apart internally from being on the truck too long.

I plan on probably changing the fluid again in 25-30k miles (it has WS in it), and will probably go to synthetic with 50k intervals after that.

I'm OK changing the filter mid-OCI if necessary, it's not too big of a deal, really. Currently I have a blue-can Pure One filter on the system.

 

[zyxelenator]

Is it engine type filter? Some filters easily hold up 15k miles. Tranny oil pressure should be lower as well as temp.Not sure, but should. So you are probably safe for 20k-30k miles with top shelf filters. If Amsoil bypass fit, probably longer...

 

[Texan4Life]

I would change it once a year... but if your like me you will get bored and change it before then.

 

[MisterBen]

Once a year seems like it would be good. It is hard not changing stuff sometimes LOL!

 

[Jim Allen]

What's all this "once a year or sooner" stuff? This is Chicken Little thinking, men!

Here are some figures for you to chew on.

On average, ATF in a trans that has never been serviced contains approximately 265 mg/l of contaminants after 70K miles of service, 90 percent of which are metallic. The particle sizes range from 5 to 80 microns, about 80 percent of them larger than 5u. Depending on the filter you use, let's say 15u absolute, you are only going to get a percentage of that percentage/

Here's a particle Count test from the trans of one of my trucks for context.

ISO Code (3) 18/17/14
>= 2 Micron 3257
>= 5 Micron 1206
>= 10 Micron 334
>= 15 Micron 129
>= 25 Micron 30
>= 50 Micron 3
>= 100 Micron 0

You are going to catch all the particles from 15u and larger and some of the smaller ones. As the filter loads up, it actually becomes more efficient (a process called sintering) so the filter gets better with age.

Ok, lets go back to that 265 milligrams per liter figure, an average developed by Engineers Eleftherakis and Khalil over decades of testing. If you have 12 quarts of fluid, that's about 11.3 liters so there is a total of about 2994 milligrams generated in 70K miles. Let's call it 3,000 mg. Divide that by 70K miles and that's .0429 mg/mile, which we'll call .043 mg/mile.

Let's say your filter can realistically catch 60 percent of that total amount, so that's .025 mg/mile. Purolater advertises their filters hold up to 13 grams of contaminants before the bypass opens, so lets use that figure.

Convert milligrams into grams and you have 13,000. 13,000/.025= 520,000. 520,000 miles to deliver a max load to a filter that can carry 13 grams. Cut it in half and you still are talking upwards of 250K miles. How many miles do you drive per year?

Consider also that you have eliminated the built in contamination as well as that which come from break-in, both of which are included in Eleftherakis and Khalil's 265 mg/l figure. They also state that 75 percent of a transmission's lifetime generation of contaminants come within the first 5K or so miles, so by changin the oil, you have greatly reduced the per mile generation of contamination.

Hopefully, I have disabused you of the need to do annual changes on your new ATF filter. In light of the above information even a 60-80K interval is way, way on the side of caution.

 

[JOD]

Originally Posted By: Jim Allen
What's all this "once a year or sooner" stuff? This is Chicken Little thinking, men!





Ummm...yeah...

Many older Subarus came spec'd with a full flow filter similar to a typical oil filter. I believe the change interval is 100K. My Freestyle has a full flow filter that is about 1/2 the size of most oil filters, and the change interval is 60K, with no time requirement. I think most owners are changing it at 100K, if at all. The media in a full-flow filter isn't going to "break down" based on time, unless you start measuring it in decades. As as you said, they just don't get that dirty.

I'd change it every 100K.

 

[MisterBen]

Jim, I appreciate your insight. It makes sense, and as I would imagine, the standard oil filter would likely not become too loaded with particulates.

We've seen filters degrade over time however, that were not really related (I would think) to "filling up". I'm MUCH more concerned of the degradation of the filter media due to age than I am overloading the filter media with particulate.

If there's no worry about degradation, I'll probably just check it occasionally to make sure nothing has struck it, and change it when I change fluid--just to get more fluid out (if I change brands next go-round).

 

[HTSS_TR]

I understand that you are concern about the degradation of the filter media due to time, but if you take into account that ATF pressure should be lower as well as temperature than engine oil, also if Honda recommend oil filter change at second oil change of up to 10k miles, then you can be sure that filter media will lasted 4-5 years if used on transmission line. If you are planning to change ATF every 25-30k miles or 2-3 years, then changing the filter at the same time is very safe.

 

[MisterBen]

Well, very good then. That seems reasonable. It seems then that if I change to synthetic, and go 50k miles, I should still be OK to just change the filter at fluid change intervals?

 

[ltslimjim]

^That sounds like a reasonable decision. Also, nice information Jim.

 

[MisterBen]

Jim, I was pretty tired when I first read your post, but I just re-read it and it's a fantastic break down.

Thanks everyone for your input, I no longer have any worries!

 

[Jim Allen]

Glad to be of help. Putting all that data together as a roadmap helped me to grasp it better as well and, hopefully, I'll get some critique (if necessary) to refine it.

I think a 5/50 interval sounds right. IMO, you are being overcautious over "deterioration" though. I recently pulled a filter out of an old Jeep engine that had been sitting in a field for decades, as well as being run for however many miles, and it showed no sign of any deterioration. When I did the first service on a recently acquired 42 year old tractor, the hydraulic filter had an '80s date code and showed no sign of deterioration. Because there is a small chance of untoward effects with old style cellulose media, you might research a synthetic media filter in the interim, which would be a deterrent. The P1s are a blend. You don't need to worry about the ADBV because it's superfluous in this application. Other than the media, there isn't much to worry about.

I haven't seen any filter deterioration documented here on BITOG that didn't have a moisture component (if you know of some, would appreciate a heads up). Water does cause problems in cellulose media but that's not something you will see in a trans. If you do, you'll have other problems. From my hands-on days with ATs in the past, significant amount of water was a death sentence as it would loosen the glue that bonds the friction material to the steel plates and cause a pretty quick failure. They may have better glues these day. Yet another research project to add to the list.

 

[MisterBen]

Interesting to hear of the old filters. When I pulled the Magnefine from the system and disassembled it, it looked perfect after 2 years and about 20k miles on the truck. That filter is pretty tiny, though I'm not sure of the media it at least looks like a miniaturized oil filter.

I have considered looking into a good long-term synthetic media filter, especially once I change over to synthetic fluids. Maybe something like the high end Fram or the new NAPA filter. As you say, probably not necessary but peace of mind for a 50k interval. I guess the only reason it made me nervous is that it's outside of the originally engineered application for the filters. If they're only intended to be on for a year or so, it made me question whether they could handle two, three, or five years in place.

 

[JOD]

I certainly understand your concern, and your reasons for it--you don't hear about people leaving on an oil filter for 10 years... But there's no moisture, and no combustion byproducts to break down the media.

Honda also use a media-type filter on almost all of their transmissions (at least the 4 cylinder ones). Most owners don't even know it's there, and there's no service interval for the filter. There are plenty of 4 cylinder Honda AT's out there with over 200K/10+ years on them and obviously the filter hasn't been a problem. So if 50K is your desired interval, I'd say you could rest very, very easy, even with a conventional cellulose or cellulose/synth blend media (like a PureOne). I'd probably choose whichever filter offered the finest filtration, regardless of it's type of construction.