ATF change in high mileage vehicles inquiry

[Kenichi_Mifune]

Hi everyone,

I work for a small but fast growing company that provides convenient maintenance service to privately owned vehicles. Something like Meineke or EZ Lube, but we are not a franchise.

I know this is an old topic, but my searches didn’t yield the answers I need.

As you know, most people have to keep their vehicles for a longer time than they used to. They have also become more concerned about the correct maintenance of their older cars.

Because of this situation, it is very important to separate myth from fact about the possibility of automatic transmission failure if the ATF is changed when the vehicles' mileage is high (65.000 miles or more) if it has never been done before.

It is a widely spread notion that changing automatic transmission oil in such conditions will cause the automatic transmission to fail because the fluid that has been in the transmission for a long time has become dirty and gritty. According to this notion, this gritty fluid is actually providing needed friction for the worn internal components of the transmission. Therefore, changing the fluid would remove this added friction supplement that the internal transmission parts now need to operate properly, which would cause the transmission to slip or suffer some type of catastrophic failure.

This concern relates both to older models using Dexron type automatic transmission fluid and also to newer models which use different types of synthetic, mostly proprietary, automatic transmission fluids.

Because this type of idea is so deeply imbedded in people’s minds, we would very much appreciate your replies or comments pertaining to the following questions:

1. What would be the best position on this issue?

2. Can the automatic transmission fluid be replaced on vehicles with high mileage when it has never been changed before?

3. Could you please provide a technical explanation to sustain your position?

Why do we ask? We ask because we need as much information and arguments as possible to provide proper and accurate replies and advice to our customers, particularly those (most of them) that believe in that ATF should not be changed in high mileage cars, as explained before.


Thank you in advance for your valuable insight on this matter.


Note: Sorry for the long post. Also, please excuse if my poor English makes reading this message difficult or unpleasant in any way.

 

[SLCraig]

With no science behind my answer I can say I have changed ATF on a few cars that had been neglected (never changed ATF) and it never once caused a problem. Again, no science. I don't know if there was wear on the transmissions or not. But they are still working to this day as far as I know.

 

[ahoier]

Fluid and filter change every 30k is my rule of thumb.....can't vouch for changing it on "neglected" vehicles though, as I'm no mechanic, or "engineer" of automobile transmissions.

I'd think either way, whatever side the customer is on, the FILTER should be replaced at LEAST. The transmisison manufacturers have the filter there for a reason, and it should at least be serviced/changed, and then topped off with new/fresh fluid at the very least....


But yea, I've heard both sides of the whole "flush" and/or "fluid exchange scenario" the pros and cons of each. I'd say, if the customer is worried about losing that "catch" from the gummed up old transmission gears, at least recommend a filter change.

 

[SZR48207]

Your grammar and writing clarity is excellent!

Regarding ATF changes, I would say that the safety of exchanging the fluid may be more of a result of driver habits and wear rather than time:

If a driver is very gentle on the car and drives in such a way that minimizes heat buildup, then there may not be any concern in swapping out the transmission fluid, even after 100k miles.

On the other hand, if you give the keys to a brand new automatic sports car to a teenager with a lead foot in the middle of the summer, you can easily burn up the transmission fluid in 5,000 miles.

This obviously doesn't help to reduce the scope of your question, but I think time alone is not a sufficient marker of transmission fluid service life.

 

[Food Scientist]

1) Change the fluid
2) Yes, change the fluid
3) The only science I need is that all of the major car manufacturer's have spent millions of R&D dollars to design their vehicle components and that I would follow their maintenance schedule, which on a lot of vehicles only require changes every 100 to 150k miles

 

[SaturnIonVue]

This isn't a direct answer to your question, and I am sorry for that, but you needn't ever apologize for your use and command of the English language around here! I must say that after reading your question and explanations, I was certainly confused by your apology at the end, since I can't seem to find spelling errors, misuse of a verb form, or anything else! If English isn't your first language, you could sure fool me! I am in awe!

 

[qdeezie]

Q. What would be the best position on this issue?

A. Do not turn down the business. A lot of falsehood is out there about ATF changes. The main thing is you have to ensure that the correct fluid is used. Sometimes even though you use a fluid that is compatible per the label, it's truly not the best fluid for that particular trans and shifting issues may occur, but that's far and few. That is probably the issue that people experience. I think it's the "oil is oil" mentality being applied to ATF that people truly don't come clean about. What I'm saying in so many words is for instance, you can have 2 bottles of transmission fluid (Fluid A and Fluid B) that are Dexron III/Mercon compatible. Fluid brand A makes it shift horribly even though the fluid is compatible per the label. You flush Fluid A out and use Fluid B the second time and the transmission shifts buttery smooth and better than it did from the factory. That would be the most likely scenario regarding worse shifting after a fluid change. A fluid change destroying the transmission is completely false, regardless of how many miles it has.

Q. Can the automatic transmission fluid be replaced on vehicles with high mileage when it has never been changed before?

A. Yes. It happens everyday. In my mind, new fresh fluid is always better than old burnt fluid. If it has never been changed before, worst case scenario, you can do the fluid change, drive for 5-10k miles and change it again and be done with it.

Q. Could you please provide a technical explanation to sustain your position?

A. Not really much technical to explain.......the old fluid is spent/burnt or whatever you want to call it and needs to be replaced. New fluid is better. This is an old wives tale about new fluid making it go bad. It's amazing how much I've seen this posted across the web. I actually read an article that stated not to change your trans fluid and drive it until failure because it's not supposed to be changed. Yes. I am serious. I've actually read this online a couple of years back. I've changed severely burnt ATF on many vehicles and I always experienced an improvement in performance because of fresh fluid. I have never lost a trans due to changing fluid.

My personal rule is that if you use a fluid that is compatible and it doesn't shift correctly, for some reason that transmission "doesn't like" that fluid. Flush it out and use a different brand and it should work better.

The obvious thing here is you have to make sure you are using the specified fluid the first time around for the best results and if it doesn't shift correctly after using the specified fluid, a different brand is more than likely required.

 

[eljefino]

I rescued a transmission that was 99% dead! Its filter was clogged with clutch dust and the pan had more clutch dust, but no metal shavings.

The line pressure was down because of the clogged filter and sheared fluid. Because of this the clutches were slipping and it was a runaway scenario.

Dropped the pan, changed ATF, filter, back to life.

Best thing for your business would be testimonials from locals with name and city on how you fixed them up.

 

[Letter_K]

http://www.amsoil.com/lit/filter_man_council01.pdf

Here is a link to the Filter Manufacturers Council bulletin on changing fluid in vehicles without dropping the pan and replacing the filter. My belief is that you are better served by dropping the pan and replacing the fluid (50%-70% of total fluid) than just flushing 100% out on an older, less well-maintained transmission. Of course, if you have a fluid exchange machine that would be good in addition to the filter change and pan drop/clean-out.

Here is a quote, that I think is relevant to your question.

Quote:
Most of the transmission failures after an evacuation (fluid exchange machine) service have occurred primarily on relatively high mileage transmissions that have not been serviced in some time. One reason for this is that the sludge and dirt buildup within the transmission will not completely be removed during the service. When the new fluid (which has detergent properties) is placed in the transmission, over days and weeks, the internal components begin to wash the insides of the transmission.

This sludge does finally work loose and settles in the transmission filter, clogging it up even further than it may have been before service. In these extreme cases, where service has not been performed in some time, changing the filter may not completely fix the problem. Some mechanics recommend a second service a few weeks after the first, replacing the filter again, which may be partially clogged due to the cleaning process in the transmission.


Of course, this is from the Filter Manufacturers Council - people who make money off of filters, so you will have to decide the value of their advice.

 

[ltslimjim]

Every 2 years, or every 30,000, seems to be a good rule of thumb if you are catching an automatic up on service that was neglected, 100,000+ etc into use without servicing. If you do it by 50,000; you'll probably be fine at whatever the manual recommends for first service and subsequent services. A filter kit costs around $15 or less for most applications. That goes at least 2 years, even in 30,000/2 year changes that are OCD on the fluid getting worn out fast.

If someone has an OCD about new fluid mixing with 50+ thousand mile fluid, research on the 'drain' via the trans cooler return line and you'll find the method that allows you to change the majority of the fluid without dropping the pan. I wouldn't skip the pan drop two services in a row, though. That is to say, 60,000+ on one A/T filter.

 

[fdcg27]

In my rather limited experience (not a big fan of automatics),
you will do no harm, and probably much good by doing a proper transmission service.
A proper service consists of dropping the pan, replacing the filter and then replacing the fluid lost in the operation.
A full flush should not be a first resort, IMHO, and a flush should probably not be done without a filter replacement.
Anyone who has done a pan drop, filter change and replaced the lost fluid in a neglected automatic can confirm that it brings a dramatic improvement in the operation of the autobox.
You won't kill a thriving but neglected automatic by doing a proper service, which must include filter replacement.

 

[gwdriver]

Off topic- KM, I am curious, are you Japanese? The reason I ask is that I was the Air Freight Terminal Manager for Japan Airlines at JFK in NY for 23 yrs. I retired from that position 5 yrs ago. My best friend had your exact name!

 

[Kenichi_Mifune]

I’d like to start by thanking all of you who took the time to reply.

The key issue here is that we are trying hard to succeed by providing the best advice to our customers in order to be able to earn their trust. I understand that this is a long term endeavor, but it should provide a solid foundation for our business.

However, even if we know that changing ATF (& pan cleaning & filter replacement) will be good for them in terms of their cars’ maintenance, it is very difficult to overcome their preconceived notions, or managing to keep them from thinking all our arguments are just a sales pitch to make them pay for something they don’t need. Or even worse, for something that may damage their automatic transmissions.

Thank you again. We will take all your comments and advice into consideration when dealing with our customers.

And no. I’m not Japanese. My nickname, is the actual name of Speed Racer's older brother, Kenichi Mifune. Speed’s name, by the way, was Go Mifune. It is a really fun fact that you actually met someone named like him.

 

[SteveSRT8]

I go with the filter mfgr's above. That is a fact.

When passive line flushing became available many people were sold as it was the 'end all be all' to fix any auto. Then the problems started.

I always tell my friends to drop the pan and change the filter first, then get a passive exchange done.