1999 Toyota Corolla Transmission fluid, to change or not to

Tiny
BNEWALL1
  • MEMBER
  • 1999 TOYOTA COROLLA
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 138,000 MILES
Hi guys, wanted to ask your opinion on 2 things related to this car (my sister-in-law's Corolla). I only recently started helping her out with some of the servicing. She's had the car since it was brand new, and it has about 138K on it now. I have no idea what it has had done to it in the past, and so far, she hasn't been able to find the maintenance records (she's moved a couple of times). She did tell me that most of the servicing has been done at oil change shops. She can't recall if she's had a transmission flush or fluid change done.

First, I've heard that in general, it's better to just drain and refill than do a full flush, since flushing can stir up particles and potentially cause damage. It's also cheaper to drain and refill.

Second, I recently read that if the car is high-mileage and has NOT had the transmission fluid changed out, and the transmission is not having problems, it may be best to leave it alone. This was due to particles in the fluid providing some of the necessary friction for the transmission clutches and other parts to function properly, and changing the fluid out would remove those particles and then you might see slippage or other problems. Since we don't know the history, I'm kind of afraid to do anything. I have a feeling that it hasn't had a drain/refill for a long time, if at all, yet it's still working, and I'm afraid to do it and cause it to suddenly have problems. On the other hand, I'd hate for her to have a sudden transmission breakdown due to lack of maintenance. What would you do? Is there a way to perhaps take a "sampling" of the fluid and see how it is? A couple of weeks ago, I had her tires rotated and oil changed, and the tire shop that did that said her transmission fluid should be replaced, but of course, they wanted to do the full-on flush and charge me $125, so I said No Thanks. But they didn't say anything specific about the fluid's condition, other than that it should be flushed.

Thanks for any help!
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Wednesday, March 18th, 2009 AT 12:36 PM

3 Replies

Tiny
JAMES W.
  • MEMBER
I'm all for changing the fluid and filter in "any trans. Changing "yes", flushing the trans and convertor, absolutely NOT. As you said, what seniment or particals that are trapped in certain areas, you want to leave there. Whatever fine particals that may come loose, that's what a filter is for.
Trans fluid isn't like motor oil where it collects carbon and needs frequent changing but it will loose some of it's lubricating ability over time. I look at new ATF as cheap insurance. I'm tied up with another poster right now but I'll look for TSBs on your tranny and if there's a new type of fluid recommended since '99 and add it to this post as an EDIT. Give me a few minuites.
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Wednesday, March 18th, 2009 AT 8:47 PM
Tiny
BNEWALL1
  • MEMBER
If you drain and refill, how much of the transmission fluid do you really get out? Before I posted this message here, I talked to a Toyota dealer that I trust, but here's what they told me:

Most of the fluid stays behind in the torque converter, so draining and refilling won't get much out. Places that want to hook up a machine and do the "flush" are often just pumping something through the transmission and torque converter to clean it out, but are not actually performing a full fluid exchange. For $120, the dealer will do this full exchange.

But what you're saying, i.E. To NOT do a full exchange, concurs with what another independent shop told me regarding my mother-in-law's 2000 Nissan Maxima. They charged me $45 to drain and refill the transmission, and said that's really all that was needed. So I guess the question is, how much of the fluid do you REALLY get out when you do that?

Thanks!
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Thursday, March 19th, 2009 AT 11:50 AM
Tiny
JAMES W.
  • MEMBER
If you leave the pan off and let the converter "siphon" down, removing about 1/2 of the fluid in the converter, the refill should take about 3 to 4 gts. This is well over 1/2 the capacity of the trans. I still don't believe in flushing but, the choice is yours. Also, you have a screen in this trans, not a filter. If the screen looks "visably" clean I wouldn't remove it for cleaning.
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Thursday, March 19th, 2009 AT 2:30 PM

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