Should I do a drain and fill the transmission fluid is very black?

GSMOORE11

MEMBER
2013 TOYOTA YARIS
1.5L
4 CYL
2WD
AUTOMATIC
340,000 MILES

I have just under 340,000 miles on it. I am almost certain it has not had anything done with the fluid in its existence. Very rarely, maybe once every couple of months, I'll feel it slip. It did it again last week and I decided to check the fluid. The level looks to be fine, but it is very black. Not thick, and I didn't feel any particulates in it. Should I do a drain and fill, or leave well-enough alone at this point?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

If this is the original transmission, chances are it is nearing the end. However, to answer your question is a little difficult.

In theory, if the fluid is extremely dirty, changing it can actually cause the transmission to slip worse. The new fluid has a detergent in it which will clean dirt from the clutches. If they are already bad, this will make it worse.

On the other hand, if the clutches are still good and the slip is due to a solenoid or dirt in the valve body, this could help.

When you checked the fluid, did it have a burnt odor to it? Also, as far as particulates, they will be laying in the pan.

Let me know your thoughts.

Joe

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Sunday, November 17th, 2024 AT 9:41 PM

GSMOORE11

MEMBER
2 POSTS

Thanks for the quick response. We're second owners with one previous, so it's all but definitely the original.

No burnt smell, just a slight/mild chemical smell.

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Monday, November 18th, 2024 AT 11:26 AM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

If it doesn't smell burnt, you may be okay draining and refilling it. That is a tough call for me from this point.

If you decide to do it, make certain you use the correct type of fluid.

Let me know your thoughts and questions.

Take care,

joe

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Monday, November 18th, 2024 AT 7:08 PM