I installed a rebuilt transmission in my 81SD 18 months and 45k miles ago. Put Mobil 1 in there. Hasn't leaked a drop since and the fluid is clear and very clean.
The rebuilder notes the fluid should be changed every 35k.
Question is can I run this any longer without causing wear? Or should I be making plans to change the transmission fluid and filter now? Anybody have information on extending between changes with synthetic trans fluid?

Transmission fluid is killed by heat. The normal temp is about 175F. For every 10F over that, the life of the fluid is cut in half.

It depends TOTALLY on your driving conditions. If you mostly cruise on the highway with very little stop and go driving then you MIGHT be okay with 45k mile changes using synth. If on the other hand you drive a good bit of stop and go traffic in ambient of 80F or better then you should be changing it MUCH more often.

How much did that new transmission cost? How much does ATF cost? If it were mine, I would be changing fluid only, in both transmission AND torque converter, at about half the normal interval and then fluid AND filter at the regular interval. If I were driving stop and go, I would be changing it so often that I would worry about wearing out the threads on the drain plug.

I am NOT a fan of automatic transmissions. I am a manual transmission maniac, but I do know how to make them live and have done so for other members of the family. The key is adequate fluid changes. These cars are VERY easy to change fluid and filter compared to many other cars. The difference is that they have drain plugs on both pan and torque converter. This makes it VERY easy and quick to do.

With an a/t the change it hot part does not apply, but the often part DEFINITELY does.

Good luck,

We all know how Larry feels about Trans Flushes

I will be picking up a trans filter and a case of Mobil 1 shortly. Thank you for the thoughts Larry.

I use mobil one in our transmissions. I change every 30k. I have been changing filters, but I am not sure if this is completely necessary every time. The filters are cheap, but it makes the job a bit messy.

I would say you get 4-5 quarts out of the torque converter and 1-2 quarts out of the transmission.... then you spill a half quart on you when you take off the cover to get to the filter.

I think if you are going to take off the cover to do the filter....get a decent size box and line it with a plastic garbage bag...this will help catch the mess...

I think you will need close to 7 quarts of fluid to re-fill it... about 6.6 or 6.7 if I recall.

lots of piece of mind after doing this job... i have found very little clutch material in the pan...

also it's interesting to compare the colors of old fluid to new... New is bright shiny red, old is usually a duller red. At least I hope yours will be red.

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Just a reminder, if you do a lot of city driving, change the fluid and filter every 15k miles to make that AT last. Even if it's a highway car, change the filter and fluid every 15k miles. City car, or highway car, changing it every 15k miles will give you a maximum AT life.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Hey,
How important is it to replace the tranny filter?

The last time I looked for a filter there were two different types to choose from. Is it stamped on the tranny somewhere?

It doesn't make much sense to go out and buy 6 quarts of mobile1 synthetic tranny fluid and not change the filter.
I guess I just answered my first question.

Also I saw this part when looking for a filter. Does anyone know what it is?

It's described as a plastic cap with pin.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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Looks like a transmission modulator pin to me.

Recently I changed the tranny fluid in my girlfriends S70 Volvo. It had 61K on it, and the old tranny fluid was nearly black, or very dark brown. I sold here on the idea of synthetic Mobil One tranny fluid. The tranny system in her car is 2 gallons. I was able only to drain 1 gallon (no drain for torque converter) and I didn't want to do the trick of removal of one of the tranny cooling lines and run it until nothing came out, so I only put back in the 1 gallon I drained using the Mobil One.

Will a 50% mix of M-1 fluid, and 50% mix of old dyno fluid present a problem?

I plan to change fluid again in 15K, thus diluting the old with new even more.

That is exactly what it is, and I might add that the tip is very brittle and snaps off easily!

OK...So.....what does it do??

I need to replace the modulator. Do I need this tool to do that?
I thought it was a simple replacement.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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It says on the bottle of mobile1 that it's compatible with conventional ATF fluids.
There was a post on here earlier about someone replacing about 1 gallon of ATF every 5 or 10K or so. Even doing that is better than not replacing it at all.

Danny

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1984 300SD Turbo Diesel 150,000 miles

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personally i would not change fluid wo the filter. the filter is to catch the particles that wear off. its not that easy to see the stuff it is catching, so why take the chance?

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

When you remove the modulator from the tranny, this plastic part in question (I don't know what it is called) is the part that transmits the modulators actions into the tranny. After you have the modulator out, you will see this plastic part installed with the pointed end extending into the tranny. You may pull this out by hand to inspect that it is not broken, but it takes a little patience putting back in. Just don't bend it, it will break!

Is changing the filter a bit messy? Need to trans oil pan to come off.
Read another thread, u need more hands than octopus to handle that?

I did the oil change by undoing the line to the radiator cooler. Using a 19mm wrench.

My last 84 Volvo , is amasing the tranny was still running at all. The old juice look like Campbell Ox tail soup, congeal a bit like jello. She has 320,000 km.
The new owner is still driving it.

How to change the torque converter's oil?