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Could changing the automatic transmission fluid be a mistake?

My friend’s 1994 Camry has 200,000 miles use. It doesn’t have a transmission problem. The fluid looks like it may be original. It’s seems thicker than fresh fluid.

Automatic transmission fluid should be changed at intervals, is the prevailing wisdom; but, if fresh fluid were put in, the viscosity would be different, and the tranmission’s performance could change for the worse.

I’d hate to tell my friend, after changing the fluid, and problems developed, that the fresh fluid was a “good thing”. Would that be believed? I knon’t think so.

At 200K miles, the tranny is at the end of it’s service life and could fail at any time. This will total the car. The last person who worked on it will get blamed for that failure…

If someone hasn’t changed their transmission fluid in 200K miles over 16 years; why would they want to change it now?

If you change the fluid, drop the trans fluid pan clean it, put in a new filter, replace the pan and fill it with Toyota brand fluid. If all goes well fine. If the transmission fails it was shot already.

Under no circumstances should you do any kind of “flush” on this transmission.

Agreed. No flushes. Fluid, filter, and gasket only, if anything.

Normally I would say there is NO downside to replacing the transmission fluid, but in this case I agree with Caddyman. At 200k miles there’s no guessing what might happen.

If the fluid is changed and all is well, you’ll be a hero. If the fluid is changed and the transmission goes (any time in the next several years) it will be YOUR fault.

I’d stay out of this one. Let the owner decide what to do.

Unless your friend has asked for your guidance, you’d be well advised to say nothing. If he has asked, then the best thing to do is refer him to the recommended maintenance schdule that came with the owner’s manual.

If your friend hasn’t changed the fluid on a regular basis (sounds like they haven’t) then the trans is on borrowed time anyway.

I agree with leaving the transmission as is. That’s the safest route to take.