Jack Rabbit
Banned
- :
- 18 Mazda CX5 AW
That's why if you didn't change it before 75000 miles, you should just drain /refill only half. Half will give you new fluid but keep some grit in there to keep the gears catching. If changing before 75 k, you can double up on the changes over a few weeks to get it all out.The high mileage trans fluid is a double edged sword. Once over 100k miles on the original trans fluid, pretty much all the additive packaging in the fluid is depleted. So the trans will begin to form varnish on parts like the valve body, hard parts, clutch plates, accumulator pistons, etc. Fluid will also lose ability to transfer heat properly and lubricate properly. Valves will start to stick and accumulator pistons will stick, etc. This can cause a bunch of problems within the trans.
If you change the fluid after 100k miles, the clutch material that is floating in the fluid is helping keep the clutch packs engaged, will be gone and you MIGHT get slippage if the clutch packs are really worn away. If you DON'T change the fluid, the trans will eventually die an early death due to the fluid being so badly deteriorated and it's inability to keep the valve body and hard parts clean. Stuck valve body parts will cause erratic trans behavior and can cause clutch packs to burn up from slippage due to not engaging the clutch packs with full line pressure.
So the moral of the story is to keep the fluid clean and service it every 60k or so, along with a filter change. Trans will live 200k+. If you don't change the fluid, the trans will most likely die an earlier death. If you change the fluid/filter after 100k miles, it might cause the clutches to slip IF the clutch packs are really worn away, and the clutch material in the trans fluid is helping to keep the clutch packs engaged while in gear.
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