Changing automatic transmission fluid

2011 TOYOTA HIGHLANDER
125,000 MILES • 4 CYL • 2WD • AUTOMATIC
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MIKEBEENE
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My maintenance book does not suggest an interval to change my transmission fluid. I have seen some information that says you never change it.

But I plan to go 300,000 miles in it so it seems likely that some interval is appropriate. There is no dipstick to check the level or be able to see the color of the fluid . Some say when it turns brown, then change it.

Does it matter if it is flushed or drained? I have heard that draining it leaves about half of the old fluid. But I have heard that flushing it can stir up gunk inside and make things worse.

What do you suggest?
Feb 23, 2018 at 8:55 AM
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ASEMASTER6371
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Good morning.

Yes, it must be serviced at the interval in your maintenance book. If you do not, then you are going to damage the transmission. All fluids in your car have time intervals to be serviced. Failure to do this will result in failures.

Flushing is not necessary. Just change the oil/filter as suggested. The flushing agent does not react well with the clutches.

Roy
Feb 24, 2018 at 5:54 AM
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MIKEBEENE
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But my maintenance book does not specify an interval or even say it needs changing. So what interval?

Feb 24, 2018 at 8:15 AM
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ASEMASTER6371
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There was a TSB about this and it recommends 100,000 for changing the fluid as most manufacturers have this mileage as the time to change.

Roy
Feb 24, 2018 at 8:21 AM
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MIKEBEENE
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Great! Thank you very much! I am overdue, so I wll get on it.
Feb 24, 2018 at 9:22 AM
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ASEMASTER6371
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Sounds like a plan. By changing it you can feel assured it will last the mileage you want.

Roy
Feb 24, 2018 at 9:40 AM