Here's a debate that I've seen in the last couple of years. Should you change the trans fluid on the auto trans, or what?
Many now say, including my local trans shop, that changing, or flushing, the fluid can actually result in damaging the trans more than letting the fluid age. If I'm understanding correctly, the new fluid is likely to dislodge dirt or particles that will then clig or damage the trans.
At what point do you change, flush, replace the filter?

 

Not to be nasty, but that is total . The auto trans has LOTS of rubbing and wearing parts with metal-to-metal contact. Changing oil and filter every 10K miles will greatly add to its longevity and its reliability. Auto trannies generate a lot of metallic particulate, mostly from normal wearout of the friction clutch plates. You need to put clean filter and oil in before that stuff clogs the inlet screen filter....or the trans will develop problems. Changing oil/filter every 10K is not required but it will keep things 'healthy'. This is for cars that see 2-3K miles per year of use. If the car sees more regular use, that mileage can be extended...but in general change it every 3 years or so, at least.

 

Been flushing mine every 15k or so since it was new, shifts great.
Some trans that are SO worn....maybe all that stuff keeps the clutches from slipping...and introducing new fluid allows it to?
Keep it clean youll be fine. Trans guy told me yrs ago to add a bottle of Lucas non slip ea time, had no issues.

 

As others have stated, total Horsesh*t!!!!

There is no such thing as not changing any car fluids never, especially Trans Fluid and filter. I have been changing trans fluid and filters religiously on every car I have owned for the last 40 years starting with my mom's 1972 Caprice with a turbo 350 all the way until today, currently with an 2008 Chrysler 300 (165,000 miles) and an 2001 Grand Prix (225,000 miles). I change the fluid and filter every 10-20,000k miles, depending on the age and mileage of the trans, more often the older and more miles. I have never had an automatic trans failure, EVER! DON"T GO TO THAT TRANS SHOP! If you change your fluid/filter often and run external trans coolers keeping the trans temps LOW, that shop and others would be out of business...no tranny failures...............

BTW-If the fluid is very old and/or extremely dirty, change the fluid/filter, drive the car for a short bid, and change the fluid and filter again, to clear out dirt more thoroughly and run a clean filter again!.

 

Do change AT fluid & filter; but perhaps Not power flush

FWIW and somewhat counter-intuitive
ALL, regardless of brand/type, ATF contains "Friction Modifiers." And, depending on type, FMs do wear out; some types sooner than others. Those FMs assist friction plates to slip, but only as they engage-disengage. That slip assist prevents the shudder that's most often associated with engage-disengage; to include torque converter lockup (engage-disengage). Many times,and in lieu of a complete ATF R&R, worn out FM's in ATF can be replaced with only a FM supplement; I've had much continued success with Lubegard's Instant Shudder Fixx. YMMV. All that FM stuff easily fact-checked.

JMO
Unlike Motor O&F, we notoriously do Not routinely service our ATs with a periodic fluid & filter change; can imagine some AT shops' very existence depends on resulting eventualities. YMMV

 

May I suggest a new transmission shop? One that does not have morons.

 

I always changed the fluid/filter in my auto transmissions until I bought a new 2006 Navigator. It had a sealed trans with no dipstick. I had 150k trouble free miles on it when I sold it. My 2018 Expedition has a sealed trans and no dipstick as well. Newer type trans fluids/parts? Believe me I don't like the setup but am I missing something?

 

metal particles could do damage to . . . . . .

Part of that statement is true. A hundred yrs ago, a machine was put in place at several of the car dealerships. They had a special, or gimmick for around $70, they would do a complete flush of the ATF. They recommended every 60,000 miles or so to have this procedure done. The mechanic tapped into the ATF coolant lines at the radiator. The machine had rubber lines that attached to the coolant lines. Basically, it was a back flush. The ATF was forced through in reverse flow. Then the mechanic showed the customer the dirty ATF that supposedly came out of their vehicle.
Was the fluid changed? Yes.
Was it done properly? No
The idea was, its fast, cheaper than dropping the trans pan. Problem was, a back flush dislodged everything in the trans filter instead of it being replaced.

 

Just to be clear, there is no such thing as a sealed transmission with lifetime fluid!!!! NONE!

A sealed transmission is called planned obsolescence..... a planned transmission life that WILL fail at some point...there is no debate about this issue and fact.

You got 150k with the same fluid?...consider yourself VERY lucky!

I know many folks with various model cars with sealed transmissions that have had tranny failures around 100K miles!!!! OR LESS.............

My freaking lawn tractor with a sealed transaxle had a premature failure as well. Guess what I do with the replacement transaxle now with the sealed tranny and lifetime fluid? RIGHT I change the fluid every 2-3 years with Amsoil synthetic hydrostatic fluid....all good 12 years in now...Hmmmmmm.

Everyone else.change your tranny fluid /filter often on any car, sealed or not, "lifetime" fluid or not.....DO NOT BUY INTO THE BS!!!

You can thank me later.....

 

So a question regarding fluid change on the transmission. As one drains the transmission, changes the filter as required what happens to the fluid that remains in the Torque Converter ? And if someone switches from standard ATM to Synthetic would you not have to "flush" the converter as it does hold a good bit of fluid.
Answers appreciated.

 

The issue comes when a transmission fluid has not been changed in a few decades. The story goes, if you change it after lack of service for many years it could clean it enough to make the transmission fail in short order. I can not testify either way but that is the tale.

 

Yes there is some risk with this scenario ^^^^^ BUT personally, I would take the risk, any day, with new fresh fluid/filter with a few fluid changes I described above back to back than with continuing to run old dirty contaminated fluid with a dirty clogged filter, hoping the latter,will not crap out at any time. Which risk would you take? I know what I would do........

 

Every 10 years i change the AT fluid & filter in my 400 that has a shift kit, got 45 years on it so far so will continue with the 10 years cycle.

 

Not a trans expert but agree with JB...keep it clean, cool it will last a long long time.
All this 100k, lifetime bs is just that, its a pitch so that trans will die. Now most cars dont even have a pan or dipstick, guess the car falls apart before the trans might who knows.

On the modern OD especially the ones with solenoids keeping it cool is crucial...Bypass the cooler in the radiator
Heck any trans behind some power, a stall converter should have one.

 

Agree^^^ for cars that are driven very little yearly and for very low miles.

My C3 is a 4 speed BUT I have a 94 Mustang GT Convertible which ran very HOT when brand new. Trans fluid was burnt at 20,000 miles and OD was shuttering. Changed the fluid in 1998, added a 24,000 Dana/Long Double stack cooler outside of the any radiator cooling (radiator by passed) and changed to Mobile 1 Synthetic trans fluid, Changed the filter, drained the torque converter of fluid too (12 Qts total). I drive this car about 500-750 miles per year and now change the fluid/filter every 10 years (later added another 18,000 GVW cooler (42,000 Total GVW cooling now). I also installed a Transgo AODE shift kit in 2010 to wake up the lazy shifts which also adds life to the tranny by eliminating slippage between shifts.

Engine coolant temps went way down, tranny fluid is always clean, shifts very quick and runs extremely cool (on a 90 degrees day high humidity, 150-155 tranny fluid temp tops)...perfect today and the way this and many other transmissions should have come from the manufacturer when made.

My 2008 Chrysler 300 and 2011 Lexus IS 350 F Sport BOTH have no tranny dipsticks which should not deter anyone from changing the fluid and filter. You would not believe what I have come up with to add a giant cooler to the Lexus Aisin Warner tranny (these tranny's are sealed and routinely fail at 100K miles or less). Just for context the Lexus "sealed" tranny has no dipstick, no filter change maintenance, no fluid change procedure or interval, and incredibly, has NO external radiator cooling, only a small heat exchanger on the outside of the transmission which is designed to HEAT the fluid quickly when cold for better gas mileage quicker...WHAT BS!

 

Someone already answered, but just because it has no dipstick doesn't mean it's"sealed". If it has a pan you can drain it, and those non-dipstick transmissions do have a fill hole.

 

They have a dedicated fill hole ... And a dedicated level check screw in the pan along with a procedure that includes fluid temp . crack open the level check screw when engine temps are reach checking temp from a scan tool while at idle rpm and fluid should small stream out of level screw on a Ford , if not fill through the fill hole until it does "small stream not drip " out of the level check screw ...GM has Cavalier , Colbolt , Grand Am with no dip sticks that have a allen screw that is located by the passenger side axle you remove and fluid should trickle out when at correct fluid temp and level while running at idle .... no such thing as a sealed unit .


Yes service the transmission because additive packages wear out

 

Yup ^^^^^same as the Lexus IS 350....but once I add the cooler I will use the trans pump to pump the fluid out one of the cooler lines and exactly replace what is removed.

2017 Cruze hatchback just bought has a filler cap, check level bolt, and drain bolt BUT NO FILTER (incredibly stupid!). The simplest way to change the fluid is to heat up the engine tranny (driving), drain the fluid and measure exactly amount removed, replace that amount, check weep hole, drive the car 30 minutes, drain again (you cannot get all the fluid with a pan drain), and repeat the procedure. No need for scan tool, fluid temp check etc. I have been doing this procedure for 12 years on my 300...no dipstick, no scan fluid check etc...works perfectly as long as you have no tranny fluid leaks and is MUCH EASIER with no hassle.....Also VERY IMPORTANT...change the fluid and filter every 10-20K miles if the car is a daily driver. DO NOT LISTEN to the manufacturer recommended fluid change intervals, if they have one. 08 Chrysler 300 is 60,000 miles. I change it every 10K. Cruze is I believe every 45K with NO FILTER (morons). I plan to change at 10K..Bought the car with 6,500 miles on it......and every 10K after that change.

 

Trans fluid does three things.....it lubricates the components, acts as a hydraulic fluid (thin), and serves as a friction modifier for trans clutch plates. The fluid is remarkably resilient as a lubricant and last a long time in that regard.....it also lasts long in the hydraulic regard.....it is sealed system so the only things you will see contaminate it are clutch material and metal shavings (few). As a friction modifier it keeps the plates happy when meshing together so the proper fluid is important. BUT....trans fluid also carries small amounts of clutch material in it that actually helps the life of the plates. I have been told many times by several sources that this why a drain/filter/fill is only 4qts or so in a 10 quart system. Flushing is fine.....but an Auto Trans that has been abused and or high mileage may experience slippage if flushed as you washed away all of the microscopic clutch material......I have been told this by a friend at Hydramatic, and several Trans builders over the years........it makes all kinds of sense to me so I drain/filter/fill.
Most important thing to do is keep the filter clean and a magnet in the pan....which most have, to keep the pump happy.
You are all welcome to flame away at this....just thought you would be interested in my point of view.

Jebby

 

I agree in theory, Jebby, with what you stated.

I also only drain the pan and change the filter on most of my cars today and going back 40 years now but I think like most things in life it is a balance of risks. The only car that I drain completely the full 12 qts of tranny fluid with a filter change is the 5.0 V8 Ford AODE since the torque converter has an access drain plug. All the other cars are pan only and filter, usually about 4 qts except the 4T65E in my 01 Grand Prix which is 7.5 Qts when you drop the pan.

Dropping the pan only along with a filter change where only a portion of the fluid is replaced is precisely the reason that 10-20K filter/fluid changes are pretty much universal by folks who know the facts and want their tranny's to last a long time. The GP mentioned above ^^^^is at 225,000 Miles on the crap FWD 4T65E with a 7.5 qts replaced with a filter and stand alone coolers every 10-20K miles max, showing zero signs that there is anything amiss with the transmission, nothing.

Keep it mind that I have never had an auto failure in 40 years on a regularly serviced transmission with external coolers regardless of age or mileage! Think about that statement and fact for a second.

Back to the question of risk, assuming that I buy the theory of clutch material in dirty fluid helping the plate life, the question is would I prefer perfectly clean tranny fluid MORE than somewhat dirtier/contaminated fluid with clutch material in my tranny, I would and do go with virgin clean fluid any day, all day.