I have a friend who just bought my old 300d (the 84). He said it's leaking ATF from the top of the transmission. His dad says put Motor Oil in the transmission. When I heard that I thought, no way. But his dad is a pretty experienced mechanic (fixed diesels his entire career and owned MB diesels) so I wonder. Anyone else heard of this?

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-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.

Do not put motor oil in the transmission.

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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

yes,
Scammers trick to make the trans run long eneough to unload the car....

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83 300SD Dark Silver Dark brown inside

Why oil? Trans fluid is not that expensive, some other reason?

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On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

He was saying that it will swell the seals and stops the leak. I said, that sounds dangerous. He said they'd run that in their MB for a long time and it worked. He had like 500k on the 220d they were driving when they junked it (rusted out and bad rear wheel bearings).

But I'm curious if anyone else has heard of this or done it. I think my friend (bought my old 300d) is planning on following his dad's advice.

I trust his dad. He's a pretty sharp mechanic. He's done some scary things (like what I just mentioned) but it seems like he's had great luck with his cars and usually knows what he's talking about.

__________________
-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.

Motor oil in an automatic is very bad.

A lot of transmission treatments or snake oils contain a petroleum distalate or petroleum oil if you wish to swell the internal transmission seals. You describe a leak at the top of the transmission. I think that is another issue.

I would go after the leak source first anyways. If the transmission otherwise operates properly you do not need your internal seals treated.

you can use motor oil in a manual tranny.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

It used to be acceptable to run diesel engine oil in automatic transmissions, was approved by Allison and ZF. ZF did caution that the shift quality could degrade. About 10years or so ago, this practice was no longer approved by Allison and ZF followed (in their heavy-duty boxes), and it will void warranties.

It is cheaper, and one fluid in larger quantities makes it simple for operators, but it is not an ATF. I wouldn't use it/

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Gone to the dark side

- Jeff

Ok that makes sense. My friend's dad worked on heavy equipment including semis so he probably experienced what you're talking about.

__________________
-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.

After getting the idea from this Forum;I put in some Lucas Transmission Conditioner and Sealer and it cured 90% of the harsh 1-2 shift and deminised the front imput shaft Seal Leak. (This was after I made sure the Vacuum Valve was working properly.)

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84 300D, 82 Volvo 244Gl Diesel

Not from anyone that knew what they were talking about.

"Conditioner and Sealers" are for transmissions on their last leg to extend their life before rebuild. Adding it to a mostly healthy transmission will shorten its life by softening seals and plugging passages.

The far better solution would have been to install the shift kit made specifically for the known shifting problems.

The only trans I've seen that uses regular motor oil was an old hydrostatic mower transmission that I changed the fluid on....I used Mobil 1 10w30....man did it improve how it drove after that! WAY faster and way smoother....and less high-oil-temp warnings when working it hard. Synthetic rocks! Even in 25 year old lawn tractors.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

some car manufactures uses motor oil as the fluid to put in a tranny ie Honda, toyotya and some american cars but Mercedes doesnt motor oil in their trannies

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)