I have an 83' 300SD that is long over due for a transmission fluid and filter change. The PO has a record of changing it at about 150,000 miles and the car now has 250,000 miles. I'm going through the whole car trying to get all maintenance items up to date. I've always heard if an automatic trany is overdue for a fluid change to just not do it, it'll go out soon after... is that true? It is shifting perfectly now. The fluid looks good and clean on the dip stick. I'd love to be able to change it out and not worry about it.

Let me know what you guys think and/or your personal experiences with changing an overdue trany.

Thanks!

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Cousin Dave
83' 300SD 250k+ and going strong!

Take the best that exists, make it better!
If it doesn't exist, create it!
Accept nothing nearly right or good enough!

CousinDave76, that's an interesting question. I can't say that I've ever heard of such a thing. That reminds me of the superstition that cars last as long as their warranty.

There may be some truth to this, but it may be due to the correlation of a long overdue change which causes a problem that prompts the need for a change. I would assume that if someone is prompted to change the fluid because of a "reason" other than preventative maintenance that there is already likely a problem.

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This area is typically used to brag about one's current or former automobiles.

The only thing I could dig up on performing an overdue change is that the new fluid may knock some built up tarnish loose and cause ports to clog up, leading to failure.

Changing my fluid would be preventive, as my trany is shifting smooth and at the right times. I just don't understand how changing the fluid would suddenly kill it, but I have heard it said so many times that I can't help but be a little paranoid.

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Cousin Dave
83' 300SD 250k+ and going strong!

Take the best that exists, make it better!
If it doesn't exist, create it!
Accept nothing nearly right or good enough!

And I will bet that you have heard it a lot more times than you have seen it. And the same is true with the people that you heard it from.

There is a small known risk. I would certainly not have it power flushed under normal circumstances. Would just change fluid and filter myself. Or at a reputable garage if unwilling.

At least you can drain the torque converter as well getting the bulk of the old fluid out on these models. The power flush just intensifies the risk greatly in my opinion. Without changing it at all the filter may become too obstructive or restrictive eventually.

Make a point of the method of getting the fill quantity of new fluid right. The archives are your best guide. More than a few have been over/under filled. These particular models seem to want some attention to reading the dipstick applied. Transmission driven till up to it's operating temperature for example before reading.

My vote is to change the fluid and filter ASAP. I picked up my 300SDL from the PO knowing that the trannie needed to have some work on it, and she honestly informed me that she had never changed out the trannie fluid. So one of the first things I did was change out the trannie fluid. Simply as that.

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Professional greasecar installer
Austin TX


98 Jetta TDI with grease car kit + veg-therm (totaled)
87 MB 300SDL running on B99 / greasecar kit + 30 fphe
www.austingreaseguys.com

Wow that's the truth! First time I ever checked the level, it took me a long time to be satisfied that I've read the actual level correctly.

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Cousin Dave
83' 300SD 250k+ and going strong!

Take the best that exists, make it better!
If it doesn't exist, create it!
Accept nothing nearly right or good enough!

Okay I am going to do it. Berry123400, I am not going to power-flush it. That does sound bad. I'll just drain and drop the pan, drain the torque converter and change the filter.

Tangofox007, I'm sure you are right. I'll not be intimidated by hearsay.

Latitude500, how many miles ago did you change the fluid?



Thanks for the replies!

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Cousin Dave
83' 300SD 250k+ and going strong!

Take the best that exists, make it better!
If it doesn't exist, create it!
Accept nothing nearly right or good enough!

The FSM says to remove the plate below the TC, but others have just let it drain, dripping on it, a bit messy, but faster.

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83 SD

84 CD

Nothing a little degreaser can't fix after the job is done. I'll most likely be a lazy boy and keep the plate intact

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Cousin Dave
83' 300SD 250k+ and going strong!

Take the best that exists, make it better!
If it doesn't exist, create it!
Accept nothing nearly right or good enough!

That falls under the old wives tales of backyard mechanics. These are the same people that will tell you going from dino to synthetic will cause leaks. If it is due change it and that way you have a fresh point to start your maint from.
My .02

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86 300SDL. 250,xxx on #14 Head. One eye always on temp gauge.. Cruising towards 300K

Use a sync. aft or better yet Trick shift.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Buffa,
I agree! its like saying that if you are late changing any fluid you shouldn't. Dont stop with the auto! Brake fluid & diff oil need to be changed as well, normally forgotten!

If it's not fairly clean and red on the stick, then change it and drive it normally for about 200miles, then change again. Fluid's cheap, trans is not, and changing it twice will get the gunk out the new fluid will stir up.
After this, change it every 36k or so.

One of the things i was taught(and some i had to learn the hard way) ALL fluids will either wear out or will get contaminated and that repair is a lot more costly

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86 300SDL. 250,xxx on #14 Head. One eye always on temp gauge.. Cruising towards 300K