I have a 2003 Tundra that I don't think has ever had transmission fluid changed

shiftyandquick

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I'm wondering if I should attempt a flush and fill. There is nothing wrong with the transmission. Less than 70k miles on the truck.

Or don't mess with it?

Just trying to educate myself on the matter, as I hear horror stories.

aggiepaintrain

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11:04p, 8/3/25

AG

My vote is : no

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CanyonAg77

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7:04a, 8/4/25

AG

No flush. Drain and refill

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sts7049

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In reply to CanyonAg77 • 7:24a, 8/4/25

AG

CanyonAg77 said:
No flush. Drain and refill

this.

i'd do it. worth making sure a low mile truck like that keeps going longer, especially if you plan on keeping it awhile.

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GrapevineAg

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9:27a, 8/4/25

AG

"An ounce of prevention…". As mentioned above, I'd do a drain and fill. Doesn't cost that much, especially if you do it yourself, your shifts will be smoother, you'll extend the life of the transmission, and you'll prevent the possibility of the torque converter shudder. Don't get me wrong, the truck will go on fine for a long time if you don't - just depends on how long you want to keep it.

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CanyonAg77

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9:31a, 8/4/25

AG

Forgot to add, that I might do another drain and fill after 5-10,000 miles, and after that at about 25,000

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GrapevineAg

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10:45a, 8/4/25

AG

If you use the engine to pump/drain a gallon at a time into a milk jug (using the transmission cooler line is easy, if equipped), and then fill with the same amount of new fluid, and repeat until what comes out is the same color as what you're pouring in, you can replace almost all of the fluid. Did this with my 4Runner (2UZ-FE engine) and it was pretty easy and made a drastic improvement (the fluid was old and had a lot of miles on it). Note: this is not a flush - there is no external machinery generating pressure in the system.

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1agswitchin4lanes

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9:04p, 8/5/25

AG

Drain and fill

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Green2Maroon

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In reply to GrapevineAg • 9:19p, 8/5/25

AG

I did this with my Tacoma. It had about 150k miles on it and I don't think the fluid had ever been changed. It made a lot more difference than I expected.

Ikanizer

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9:15a, 8/6/25

AG

What does the owners manual recommend?

Dill-Ag13

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9:23a, 8/6/25

AG

Can do a few quarts at a time and change it every 6 months to slowly refresh the system if you are worried about shocking it.

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1agswitchin4lanes

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In reply to Dill-Ag13 • 5:26p, 8/7/25

AG

Dill-Ag13 said:
Can do a few quarts at a time and change it every 6 months to slowly refresh the system if you are worried about shocking it.

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shiftyandquick

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9:10p, 8/7/25

Thanks for all the input guys!