It's time to service my automatic transmission - I know this must be an old topic, but what is the most-recent net wisdom about using synthetic ATF in these older MBs? (mine is a 1981 300D).

My mechanic consultant is hesitant on this - thinks original and now aged seals are not up to the task.

What do you think?

Thanks,
Erlend

It is entirely possible, however I would say that it is best to go synthetic now while the gaskets are still readily available. Vs 10 years from now.

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1995 E420 Schwarz
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#1995 E320 Touring
#1985 300D Sedan
OBK #42

Synthetic is almost always a good option unless it has a gazillion miles or it leaks alot.

I put Mobil-1 synthetic ATF in my '85 300D (230,000 total miles to date). The transmission was relatively new (rebuilt a few years ago by a PO, it had fewer than 50,000 miles). No problems with Mobil-1 in about 13,000 miles so far.

OTOH, I did the same thing with my '96 E300D, which has a very similar tranny (both are 722.4's) but 250,000 miles on it. Small leaks had been noticed by the first owner's dealer as early as 180,000 miles; the Mobil-1 found these leak spots and used them with a vengeance. I ended up having the transmission rebuilt so that the leaking seals (mostly the front pump seal) could be replaced. $3000!!! The mechanic said that the wear parts other than the seals would have been good for at least another 50,000 miles, oh well.

Mobil-1 won't cause leaks but it will find any that already exist. Since synthetic oil is composed of smaller molecules, it can get out through tiny spots that stop regular oils, or so I have been told.

In my '85, I noticed no change whatsoever in the performance of the transmission -- it shifted properly before and after changing to Mobil-1. No difference in noise levels, etc. Consequently, I would recommend using just a good quality regular transmission oil -- pick some brand that you like. Change the filter, pan gasket, drain both the pan and the torque converter, drive your car and enjoy it.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I have the same year 300D as JEREMY an 85, where he had fewer than
50000 miles on his rebuilt transmission, I ****ed my transmission over to
synthetic ATF at 330900 miles.

I replaced the K-1 kit at that time, new filter and 6 plus qts of Amsoil
ATF. I have no leaks at this time, but I have only driven about 4400
miles so far. one trip to Phoenix, Az. and one trip to Carson, City NV.
So most of my driving has not been around town.

The transmission has never shifter as well as it does now. much smoother
than before. so I don`t know if the K-1 or the ATF did the trick, or a
combination of the two.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I switched to mobil 1 syn ATF shortly after a trans rebuild at 100k and now have 270k - no problems at all. In an used trans I would add an additive containing a seal softener/conditioner such as 'BG ATC Plus'.