# Time or Miles?

**URL:** <https://community.cartalk.com/t/time-or-miles/179387>\
**Category:** Maintenance/Repairs\
**Created:** [September 15, 2021, 4:16pm UTC](https://community.cartalk.com/t/time-or-miles/179387 "2021-09-15T16:16:51Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![melott](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/melott/32/10827_2.png) [@melott](https://community.cartalk.com/u/melott)\
**Post date:** [September 15, 2021, 4:16pm UTC](https://community.cartalk.com/t/time-or-miles/179387/1 "2021-09-15T16:16:51Z")

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Is it true that brake fluid is best replaced based on time, but tranny fluid based on miles driven?

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**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\
**Post date:** [September 15, 2021, 4:26pm UTC](https://community.cartalk.com/t/time-or-miles/179387/2 "2021-09-15T16:26:51Z")

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Yes, time on brake fluid, miles on tranny fluid.

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [September 15, 2021, 4:27pm UTC](https://community.cartalk.com/t/time-or-miles/179387/3 "2021-09-15T16:27:51Z")

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Yes!

Brake fluid absorbs moisture from the air even if the vehicle isn’t being driven.

Transmission fluid breaks down over miles driven.

Tester

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<div class="post-metadata">

**Author:** ![melott](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/melott/32/10827_2.png) [@melott](https://community.cartalk.com/u/melott)\
**Post date:** [September 15, 2021, 6:38pm UTC](https://community.cartalk.com/t/time-or-miles/179387/4 "2021-09-15T18:38:00Z")

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many thanks