To change or Not to change automatic transmission fluid

[Evil Sports]

So my son turned 16 this month and I have as part of my fleet a 06 Scion Xb with 170k on it. I have that slated as his first car. I figured I would go through it one last time and make sure it has what it needs to last him a couple years. One thing I realized is we never changed the auto Trans fluid since we owned it. Should I mess with that now or is it one of those better to leave it alone things.

 

[txav8r]

I don't know Bob, what does the service manual call for? Both of my vehicles are hybrids and those have very different transmissions. But I know from the past, I watched the fluid color and smell, and changed it around the 100K point if I remember correctly. Come on guys, more input!

 

[Bruce]

I changed the ATF in my Sierra Denali around 100k miles. The manual said to do so under harsh conditions. I thought I was doing a good thing. 40k miles later I replaced the transmission. Several mechanics said that the detergent in the new fluid had caused the problem.

 

[Wayloncle]

I've heard lots of different things about changing the fluid. I do know if you do it make sure it is a complete flush, the torque converter holds a whole lot of fluid.

I flushed mine in my truck about 6 months ago at 77K miles. I did it because the color had changed a lot and I have a lot of miles pulling my camper and such.

 

[GiddYupJoe]

I changed the ATF in my Sierra Denali around 100k miles. The manual said to do so under harsh conditions. I thought I was doing a good thing. 40k miles later I replaced the transmission. Several mechanics said that the detergent in the new fluid had caused the problem.

I'm at 110k on our Tahoe and the transmission fluid is part of the 100k service. I had the rest of the service done except the tranny. Every mechanic I talk to tells me something different and the Chevy forums, well it seems to be like fogging or no fogging!

Sorry I am no help to answer your questions but I am interested in what you all have to say on this subject.

 

[Murf'n'surf]

Too funny! Today while getting my oil changed at Valvoline, I decided to pay the $149 to have my transmission fluid changed for the first time (153,600 miles). Yes, way over priced but I can't even find time to install my new Cobra Fins! I would get it changed especially if those miles were city stop and go although @Bruce has me a little freaked out about the detergents.

 

[Seadeals]

8 years and 170k sounds like plenty of time, mileage, moisture/contaminent ingress and heat exposure/chemical breakdown to constitute a change. Good to check the manual; but I can't imagine it would not say to change by now. Regardless, I'm a big follower of OEM tech data; but we don't ALWAYS follow the manual, now do we? Plus since it is your son...I say take the plunge. New brake fluid too. Moisture can really mess with brake systems and you want to make sure they work REALLY well for him. For some reason my brakes never seemed to work quite well enough when I was 16...oops.

 

[MikeyL]

"To change ... or NOT to change ..."
What we have discovered is really simple and works long term .....
At least in THIS case:
DO WHAT THE MANUFACTURER'S MANUAL RECOMMENDS !

This rule will save your a lot of aggravation, worry, mistakes and wasted dollars.
Hey ! Merry Christmas, y'all ! Mikey Lulejian - Lake Oconee, GA

 

[woodard1983]

I changed the ATF in my Sierra Denali around 100k miles. The manual said to do so under harsh conditions. I thought I was doing a good thing. 40k miles later I replaced the transmission. Several mechanics said that the detergent in the new fluid had caused the problem.

chevy's tranny fluid is different than the other brands....you have to make sure to use the GM stuff or it will most likely have an ill effect.....the rule that I have stuck with and has worked on all of the vehicles I have owned.....chevy/gm-don't touch it and you'll be fine for at least 200k miles, for some reason w/them if you open it up it seems to cause problems :/ all other brands I've changed at the scheduled points and have been fine

 

[woodard1983]

"To change ... or NOT to change ..."
What we have discovered is really simple and works long term .....
At least in THIS case:
DO WHAT THE MANUFACTURER'S MANUAL RECOMMENDS !

This rule will save your a lot of aggravation, worry, mistakes and wasted dollars.
Hey ! Merry Christmas, y'all ! Mikey Lulejian - Lake Oconee, GA

View attachment 15303

see @Bruce's example above...this is not always true

 

[Evil Sports]

Thing is these work cars dont usually hang around here much after 100k miles so I never really thought about tranny services. The scion has been a sales car for a while and I didnt even think about the mileage

 

[Bruce]

chevy's tranny fluid is different than the other brands....you have to make sure to use the GM stuff or it will most likely have an ill effect.....

The factory fluid was replaced with the correct fluid. My transmission was a complicated situation. I have a 2007 Sierra Denali which was one of the first 6.2 liter and six speed transmission combinations. In 2009 GMC changed the first drum housing after discovering that the drum had a tendency to crack. My guess is that the drum was cracked on my transmission and changing the fluid cleaned out the crack. Surprisingly when we replaced the transmission we found a 2008 transmission in the truck. So it is possible that it had been changed before.

It is possible that if I had not changed out the fluid I would be here saying that I wish I had. But since I changed it I am here saying that changing the transmission fluid likely cost me $4k.

 

[KXCam22]

I did a lot of research on that topic years ago when I bought a new truck. There was a lot of evidence (although anecdotal) that changing the ATF at high mileage was detrimental. The accepted reasoning was it stirred up the deposited sediments in the trans which then caused a failure reasonably soon after. I changed my new tundra ATF at 20K to get rid of the break in wear metal particle. Now that I am at 200K I am not sure what to do. I wonder if you did a change without the "flush" if that would help. Cam.

 

[motorboater]

If the fluid is badly burnt or discolored (which likely means the damage is already done) I'd just drain and fill rather than flush. Use original equipment fluid and filter from the dealer. Yes the torque converter holds a lot of fluid, but you will remove enough old fluid to replenish the additives. Do it about twice as often as the manual recommends if you are concerned about it, just to increase the ratio of old vs new fluid.

Now, that being said, my 1998 Chev Z71 which I bought brand new and now has 210k miles on it, is still rocking the original fluid, which still passes the look and smell tests. This is because I know of 2 specific cases amongst people I know personally who both ended up replacing their transmissions on the same model vehicle not long after having a fluid flush done. Also my transmission started failing on my 330i within days of having a fluid flush done at 130k. I traded it in immediately (and immediately had to put a new transmission in the low mileage X5 I traded it in on). Karma I suppose.

Our Honda Accord has never had a flush done since we've owned it and I dont plan to. Going forward my strategy is to follow the manufacturer recommendations on any future vehicles, however never doing a full flush. Just a periodic drain and fill, and new filter if it applies. Most new vehicles use "lifetime" fluids which basically just means leave it be until it doesnt work anymore, then install a reman unit. If you sell/trade the vehicle before it sees 100k miles it will likely be the 2nd owner's problem.

 

[octavio3311]

As for the GM's - I've been told by several techs "don't change the tranny fluid - doing so usually leads to problems".
My brother is running a Chevy Express with 280k (and counting) miles on it. He's been told the same thing.

 

[Big Shasta]

I would do a drain and fill at the next 3 oil changes.....gradually working into the new fluid. I hear it a lot but the whole "it's too late to change it" theory just gets rejected by my brain every time I hear it.....I just don't see how the old worn out fluid could be better to just leave in. Make sure you use the Toyota/Scio Fluid, it's expensive but you don't want to chance it with aftermarket stuff in a trans.

Also, +1 on changing the brake fluid. I have a pheumatic brake bleeder that is awesome, I hook it up to the bleeder port, start the suction and just keep filling the reservoir until the clean fluid is coming out. It should be flushed every 2-3 years expecially in humid climates, it's hygroscopic (absorbs water) and the boiling point gets lower over time....boil the fluid at the end of a long hill and it's bye bye braking.

 

[buckbuck]

Wow. You guys are making me feel like an outcast. I change the fluid on my Fords about every 40,000 miles. It is easy to do. Transmissions are extremely complicated equipment and are very dependent the hydraulic fluid having the proper slip/friction ratio.
As far the original post, I don't have any experience. But when you drop a transmission pan there is a large magnet that collects all the iron particles. Seems to me that it would be best to change it.

 

[Murf'n'surf]

Years ago, I remember dropping the pan on Ford trucks and replacing the trannny filter. Is this still recommended of today's transmissions? I only ask because nobody has mentioned a filter change.

 

[Big Shasta]

Most don't have serviceable transmission filters anymore. My Tundra doesn't even have a transmission dipstick. Blew that one Toyota.

 

[buckbuck]

Ha. I guess it makes sense why I am out of touch. My newest vehicle is 10 years old with 130,000 miles.