Changing the transmission filter un-needed?

[stchman]

I have read that changing the filter in automatic transmissions is usually un-necessary. I happen to agree.

I worked in the quick lube industry for many years and when we did transmission services the filters (some were simply wire screens) were rarely ever dirty. The ones that were "dirty" were usually as result of exceptionally un-maintained fluid (almost black) and the transmission's days were numbered.

Since an automatic transmission is essentially a closed system(unlike an engine that sucks in HUGE amounts of air and burns fuel), so the fluid does not accumulate large amounts of dirt. The only thing that happens to the fluid is that the heat breaks down the additives and the fluid can change viscosity. Honda automatics don't have a pan to take down and drain, and their automatics last a good long time if the fluid is drained and filled at the specified interval.

Just wanted people's thoughts.

 

[bdcardinal]

I always do it at least on the first change the vehicle gets.

 

[Falken]

The clutch packs shed abrasive material and metal, there are a lot of things in an AT that make the fluid abrasive, not only thermal breakdown.

Enough to load a filter over the life of the trans? Probably not, but I'd change it anyway if the pan was off.

If you look at some used oil analysis for ATs you'd be surprised at the FE content.

 

[Phishin]

I don't change the filter either. Waste of money.

As a matter of fact, when I bought my wife's Subie 1.5 years ago, it was 5 years old with 44k miles on it, I dropped the pan and wiped it clean, and never changed the filter. I was right there, and I could have easily done it, but it was spotless.

Why change these things? Just to do it?

I agree, if the transmission fluid is nasty and service history is unknown on a high mileage vehicle, it's a good idea to at least look at it.

Only reason I dropped the pan on her Subie was because every time I pulled the dipstick, there was one or two small grey flakes found on it. I guess it was nothing.

 

[3800Series]

The filters are mostly rated for 50k miles I've heard. Since most people either never change the fluid or change it every 25k miles it's worth a change. Its a few penny's more if you get the filter gasket combo.

I'm all seriousness tho I would change it. Changed my Regals several months back and it looked like the factory filter. It was hard and near dry rotted. Cracked and broke off with little pressure. Worth getting it out now to insure a good one for future changes.

The filter will collect some metal shavings/dust depending on the manufacturer of your vehicle. Some use metal screens some use true filters. If your car is Asia/Euro odds are it has a metal screen that can't be serviced.

 

[stchman]

Originally Posted By: 3800Series
The filters are mostly rated for 50k miles I've heard. Since most people either never change the fluid or change it every 25k miles it's worth a change. Its a few penny's more if you get the filter gasket combo.

I'm all seriousness tho I would change it. Changed my Regals several months back and it looked like the factory filter. It was hard and near dry rotted. Cracked and broke off with little pressure. Worth getting it out now to insure a good one for future changes.

The filter will collect some metal shavings/dust depending on the manufacturer of your vehicle. Some use metal screens some use true filters. If your car is Asia/Euro odds are it has a metal screen that can't be serviced.


Of all the transmissions I dropped the pans on and changed the filter, NONE of the filters had dry rotted plastic. How can plastic dry rot if it is continually submerged in ATF?

From what I have read, the filter(screen or fiber element) is back-washed when the engine is shut off. The filter is there just to keep any large matter from being sucked into the valve bodies.

 

[3800Series]

Originally Posted By: stchman
Originally Posted By: 3800Series
The filters are mostly rated for 50k miles I've heard. Since most people either never change the fluid or change it every 25k miles it's worth a change. Its a few penny's more if you get the filter gasket combo.

I'm all seriousness tho I would change it. Changed my Regals several months back and it looked like the factory filter. It was hard and near dry rotted. Cracked and broke off with little pressure. Worth getting it out now to insure a good one for future changes.

The filter will collect some metal shavings/dust depending on the manufacturer of your vehicle. Some use metal screens some use true filters. If your car is Asia/Euro odds are it has a metal screen that can't be serviced.


Of all the transmissions I dropped the pans on and changed the filter, NONE of the filters had dry rotted plastic. How can plastic dry rot if it is continually submerged in ATF?

From what I have read, the filter(screen or fiber element) is back-washed when the engine is shut off. The filter is there just to keep any large matter from being sucked into the valve bodies.


Sorry I hadn't meant dry rotted in the sense just couldn't think of the proper explanation. Its been a long day here. Brittle would have been a better word, My apologies.

 

[The_Jeff]

If you lay a 100k mile dipstick on a paper towel, odds are good that it will wick a little grey matter, which is the clutch stuff in suspension. I'd love to capture more of said stuff.

 

[bullwinkle]

Originally Posted By: stchman
Originally Posted By: 3800Series
The filters are mostly rated for 50k miles I've heard. Since most people either never change the fluid or change it every 25k miles it's worth a change. Its a few penny's more if you get the filter gasket combo.

I'm all seriousness tho I would change it. Changed my Regals several months back and it looked like the factory filter. It was hard and near dry rotted. Cracked and broke off with little pressure. Worth getting it out now to insure a good one for future changes.

The filter will collect some metal shavings/dust depending on the manufacturer of your vehicle. Some use metal screens some use true filters. If your car is Asia/Euro odds are it has a metal screen that can't be serviced.


Of all the transmissions I dropped the pans on and changed the filter, NONE of the filters had dry rotted plastic. How can plastic dry rot if it is continually submerged in ATF?

From what I have read, the filter(screen or fiber element) is back-washed when the engine is shut off. The filter is there just to keep any large matter from being sucked into the valve bodies.
Think he meant hardened plastic from heat damage, in the few I've done I've had one or two snap off on removal too.

 

[Donald]

Install a Magnefine inline filter and change it every 30K. There will be metallic paste on the magnet but little in the media section.

 

[MolaKule]

Originally Posted By: Falken
The clutch packs shed abrasive material and metal, there are a lot of things in an AT that make the fluid abrasive, not only thermal breakdown.

Enough to load a filter over the life of the trans? Probably not, but I'd change it anyway if the pan was off.

If you look at some used oil analysis for ATs you'd be surprised at the FE content.

And clutch particle content as well.

Why risk a restricted filter when, if you have the pan dropped, just change it.

 

[stchman]

Originally Posted By: MolaKule
Originally Posted By: Falken
The clutch packs shed abrasive material and metal, there are a lot of things in an AT that make the fluid abrasive, not only thermal breakdown.

Enough to load a filter over the life of the trans? Probably not, but I'd change it anyway if the pan was off.

If you look at some used oil analysis for ATs you'd be surprised at the FE content.

And clutch particle content as well.

Why risk a restricted filter when, if you have the pan dropped, just change it.


Agreed, but are these reasons to not do a simple drain and refill and drop the pan and change the filter.

 

[DoubleWasp]

The 100k mile filter in my ZF was merely stained. Complete waste of time changing that filter.

 

[HangFire]

Changed the filter on my Corolla around 70K (forget exactly), there was a thick layer of silvery paste on top of it.

I'm changing it again soon.

 

[turtlevette]

Originally Posted By: MolaKule
Originally Posted By: Falken
The clutch packs shed abrasive material and metal, there are a lot of things in an AT that make the fluid abrasive, not only thermal breakdown.

Enough to load a filter over the life of the trans? Probably not, but I'd change it anyway if the pan was off.

If you look at some used oil analysis for ATs you'd be surprised at the FE content.

And clutch particle content as well.

Why risk a restricted filter when, if you have the pan dropped, just change it.


I believe the filter is too coarse to catch small suspended particles. This is why you still see them. There is a very good reason not to change the filter. Its because many people hose it up. The gm stuff retains the filter o ring in the valve body and it can be very difficult to get it out. As a result these o rings often get sucked in by the pump causing transmission failure. Then people blame it on the maxlife fluid instead of their own incompetence.

 

[Lubener]

I would change the filter periodically. As the filter loads up with debris, the transmission is slowly starved for fluid flow.There's no bypassing like an engine oil filter.Crud also accumulates on the bottom of the pan and some cars have a magnet in the pan that attracts gunk.

 

[Phishin]

Seriously? EVERY transmission filter I've ever seen, which is only on 5 vehicles (1990 Chevy Truck, 1999 Chevy Silverado, 2000 Nissan Altima, 2009 Subaru Forester, and 2010 Honda Accord), all the transmission filters looked like rock catchers.

They can't filter ANYTHING, unless it's the size of a pea.

 

[nicholas]

What about all the clutch pack material - - even if the car is driven mildly - this alone is a good case to replace the fluid and check the magnets.

The screens are a very poor method of filtration - - very common in Asian transmissions. Our last Audi had a huge cloth filter in the transmission.

 

[MolaKule]

Quote:
I believe the filter is too coarse to catch small suspended particles. This is why you still see them. There is a very good reason not to change the filter. Its because many people hose it up. The gm stuff retains the filter o ring in the valve body and it can be very difficult to get it out. As a result these o rings often get sucked in by the pump causing transmission failure. Then people blame it on the maxlife fluid instead of their own incompetence.


Are you speaking of the course "strainers" in, for example, the Nissan Transmissions, or the filter in the plastic filter assemblies such as the GM or other transmissions?. The strainers aren't filters.

Neither I nor my mechanic have heard of any problem with any o-rings being sucked up into the internals by any competent service group. Nor are they difficult to remove.

I have seen the synthetic filter material in the filter assemblies laden with clutch particles, which is what these filters are designed to trap.

Replacing the fluid refreshes the additives and gets rid of many particulates.

Wiping the pan and cleaning the filter magnet also insures nothing gets washed back into the transmission.

 

[mrdctaylor]

The only time I've ever changed one was when my folks gave me their 2002 Chevy Trailblazer with 150K miles. It had never had a transmission service. I was dropping the pan anyway (no drain plug) and figured WTH. I have no idea if the old one was still OK or not. I'm sure it was, but I needed the gasket anyway, so why not get the full kit?

As for my 2002 Tacoma and 2003 Santa Fe, they have drain plugs. I do drains/fills every 30K miles. Both are pushing 200K miles with zero issues. I'll continue with that schedule. I'm doing the same with my 2012 Highlander. Partial fluid changes only--no pan drops.