So I was going to change my tran filter and fluid today but someone convinced me to but a transmission flush can of sea foam. I was going to put it in with the fluid and run for a couple hundred miles and then change the fluid and filter afterwards. Good idea? Bad idea?

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1984 300d....

If the trans is ok, don't do it. If you do the trans service properly - draining the torque converter, you're getting all the fluid anyway. You're opening Pandora's Box if you do anything otherwise.

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
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Do I miss being a service advisor ???

I think that it is a good idea to clean the varnish out of the valves and soften the seals every ten years or so. Seafoam makes a good product.

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Dave
1983 300D Daily Driver

Hmmm. Conflicting views.... Well the car has been sitting for at least 4 years and probably longer. The transmission seems to shift fine but I'm thinking it wasn't serviced very well prior to that.

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1984 300d....

If it were me - I would stick to draining the torque convertor and changing the filter. Maybe you have some built up deposits (maybe? probably?) depending on the previous service interval - I for one would be concerned about what might happen if you suddenly knocked all the deposited material loose in one go.

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

That's what worries me. So I guess just drain and change filter? Nothing else to worry about?

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1984 300d....

Safest bet, unless you're itching to buy a trans..

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
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Do I miss being a service advisor ???

You do not get all the fluid out with a filter change and converter drain. There is fluid in the cooler and lines as well as fluid in the clutches. The only way to change all of the fluid is under pressure.

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Dave
1983 300D Daily Driver

Just drop the pan, and change the filter along with draining the t/c. Doing, anything more increases the risk that it will die a rapid and instant death.

Well thanks! Why does this product exist???

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1984 300d....

Because people will buy it.

ATF is a very high detergent hydraulic fluid, cleans on its own.

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Gone to the dark side

- Jeff

Don't forget to scrub that transmission pan.

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1985 CA 300D Turbo , 213K mi

I wouldn't do that to an old trans, thats just asking for trouble. You don't want to losen whatever is inside up, let it stay their. All you will do is clog the filter or valve body, and before you know it you lose a gear.

I have actualy had decent luck with Trans X swelling up the seals to slow down leaks.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I used it in my motor right before my last oil change, poured it in and drove about 20 or so miles and then changed the oil. But using it in the tranny????

Doc.