Transmission fluid change?

MRANCK79

MEMBER
2016 TOYOTA HIGHLANDER
6 CYL
4WD
AUTOMATIC
115,000 MILES

I've been good at keeping up with recommended service on my vehicle listed above. Most of the work has been done at the dealership where I bought the car. I was recently informed they don't have record of the transmission fluid ever being changed. This surprised me given my opening sentence. It has 115000 miles on it. I've checked the other auto service center where some work has been done, and they have no record of changing the transmission fluid. I called the dealership back and scheduled to have the fluid changed. The tech advised me that if it hasn't ever been changed, changing it now may do more harm than good because the transmission has been conditioned (my word) to function with dirty fluid. I was surprised with this statement, especially with the reputation of dealership service departments always recommending some service to get money in the door. Does this make sense to you about changing the fluid now doing more harm than good?

Friday, January 10th, 2025 AT 2:14 PM

5 Replies

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

What he is saying may be correct. If the present fluid is excessively dirty, it may be allowing the trans to keep working.

When you install new fluid, it has a cleaner in it. It will help wash away the dirt that is built up and sometimes, it can allow the clutches to slip.

To check the condition of the fluid is somewhat of a pain because of how it is done. The engine needs to be running, the transmission at operating temp, and then the fill plug on the transmission is removed. With it running, oil should just trickle out. If nothing comes out, it needs fluid added. If they were to do that, one should be able to determine how dirty the fluid is and make a determination if servicing it is a good or bad idea.

Do you know if they even inspected the fluid? I attached a pic showing the fill location.

Let me know.

Joe

See pic below.

Image (Click to make bigger)

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Friday, January 10th, 2025 AT 8:25 PM

MRANCK79

MEMBER
3 POSTS

Thanks for the information. They have not inspected the fluid.

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Saturday, January 11th, 2025 AT 7:24 AM

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

JACOBANDNICKOLAS please let us know what happens.

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Monday, January 13th, 2025 AT 12:32 PM

MRANCK79

MEMBER
3 POSTS

Someone more competent at the dealership was able to pull up all the service history and determined the fluid was changed around 65K miles.

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Monday, January 13th, 2025 AT 12:37 PM

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

Thanks for that update. That is a good thing. I wouldn't be afraid to service it at this point.

Let me know how everything works out for you.

Take care,

Joe

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Monday, January 13th, 2025 AT 5:41 PM