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Should I change my ATF


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Scotty, we inherited a 2002 Toyota Highlander (limited ed loaded) when my parents died (it WAS the car that the little old lady drove to church on Sunday), it has 140k miles and runs fine.  I was considering changing the transmission fluid according to your videos next oil change.  Am I asking for trouble?  Never been done to my knowledge, but it looks a bit grungy to me on the dipstick.

Since I found your YouTube my wife has become a Scotty Kilmer widow, she says I don't talk to her anymore 'cause I am always watching your videos.

What do mean by "grungy"? What is the color on the dipstick?

2 Answers

Please read the FAQ topic.


Posted by: @blacksmith

looks a bit grungy to me on the dipstick.

Here’s a pic of the internet that explains it

If it’s burned or has chunks in it - don’t.

For the rest that’s probably going to be ok.

I disagree. Burnt fluid should definitely be changed, otherwise it'll lead to transmission failure. I've done so several times.
Fluid can get burned up in the torque converter, and it doesn't necessarily indicate clutch wear.
It's the gritty fluid one needs to look out for.

Not all bad fluid is caused by friction dust (some of it rarely is metallic, but usually friction dust), but usually it is - but what matters is that dust has been circulating though the valve body.
From my experience with Koreans and Euros, 6 or 7 /10 times when replacing burnt fluid, the car comes back after 5k-15k because it began to shift poorly (they rarely slip, usually it's just hard shifting)
I talked to people abroad who actually repair valve bodies and even solenoids instead of repairing them (actually replacing the core of the solenoid, very useful when the manufacturer doesn't sell new parts - like Subaru) and according to them it has to do with the dirty fluid wearing out internals and the worn fluid having particles in it essentially won't pass / bleed though worn (enlarged) clearances.
I'm unsure how true that is, usually if it shifts funny you just check how much is a rebuild kit + labor is compared to a used one without going into much detail.
On a "toy" and a sentimental vehicle, that's not driven much why would you take the risk? It probably can go another 20k-30k before requiring a repair (and on a toy, as suggested by the title, that can be many years)
These old Toyota transmissions have great reliability, but they're quite complex and I'd imagine it's not going to be cheap to fix or find a good replacement with reasonable milage.

That's what I'm saying ... particles.
Fluid gets burnt/brown because the base oil is cooked and oxidized from heat - but that doesn't mean it has particle contamination in it. In this case it, the fluid should be changed.