A slightly different oil thread

[Mark DiSilvestro]

So, I've been getting 'Ol' Blue', my recently-acquired '82 240D, ready for a trip next week, and I remembered from a recent thread that the manual tranny in this car takes engine-oil. Sure enough, my 240D owner's manual calls for 10W20 engine-oil. Minor question - since my local autoparts stores don't seem to stock 10W20, is 5W20 OK.

But my main question is - I also checked the owner's manual for my '84 Euro 5-speed 300TD, and it calls for ATF in ALL W123 manual trannys, including 4-speed and 5-speed, 240D and 300D. I know earlier Mercedes manuals required ATF. Does anyone here know why ATF would be specified for Euro W123 manual trannys, but engine-oil is listed for the US version? Thanks.

Happy Motoring, Mark

[rs899]

I'm not sure what the 240D book says, but if it does say 10-20W, I would use 10-30W instead myself rather than going that thin. Better yet would be to find a good synthetic- Redline MTL is what I use in everything.

Rick

[Muddin]

Per my official service manual for my '77:

[Mark DiSilvestro]

Well, I only added about 1/2 quart of 5W20 and it holds 1.4 quarts. It had some sort of clear oil in there, not like ATF, and my owner's manual clearly states 10W20 engine-oil. I also popped the wood shifter-cover and lubed the lever pivot, which was feeling stiff and gummy. Now it shifts smooth and easy.

I too have a copy of the factory transmission manual, printed 1980, covering models from 1977, that specifies ATF. However It's my understanding that Mercedes replaced the iron-case manual-gearbox with the new-design aluminum unit in 1981, which of course isn't covered in my factory manual.

And my Haynes manual, which is supposed to cover the W123 diesels through 1985, is typically worthless on this detail, as it specifies ATF, but only covers the older iron-case design in the manual-tranny chapter.
However, my '84 Euro wagon's 5-speed does have an aluminum-case yet that owner's manual specifies ATF.
It's all rather perplexing.

Happy Motoring, Mark

[Muddin]

In general if you have an aluminum transmission case you use ATF.

Do you think it might be gear oil that's in there?

[Mark DiSilvestro]

Originally Posted by Muddin

In general if you have an aluminum transmission case you use ATF.

Do you think it might be gear oil that's in there?

No. It was definitely thin and didn't have that gear-oil smell. I remember it used to be a big no-no to use gear-oil in a Mercedes manual tranny. Supposed to damage the synchros or needle-bearings or such.

I remember as a teenager filling the manual tranny on my '61 Ponton 180b with gear-oil, only to discover that my owner's manual called for ATF, so I got to drain and refill it again!
I know Hondas used to specify motor oil in their manual gearboxes, so I wasn't suprised when someone posted here recntly about requiring motor oil in the manual-tranny of an 83 240D. At that time I also verified this in my '82 240D owner's manual.

Now if someone could prove that Mercedes made a mistake when they printed my 240D owner's manual... Or maybe Mercedes changed from ATF to engine oil in the US to satisfy some obscure EPA or DOT regulation. Like the regulation that prevented Mercedes from including safety triagles on their us-market models!

Happy Motoring, Mark

[Diesel911]

My Volvo Diesel manual Transmission also uses ATF.
It also has an Aluminum Case.

[Muddin]

Originally Posted by Mark DiSilvestro

Now if someone could prove that Mercedes made a mistake when they printed my 240D owner's manual... Or maybe Mercedes changed from ATF to engine oil in the US to satisfy some obscure EPA or DOT regulation. Like the regulation that prevented Mercedes from including safety triagles on their us-market models!

Happy Motoring, Mark

I've seen where some manufactures changed from gear oil to ATF or motor oil simply because it improved shifting for the driver.


Here's some info on the viscosity of ATF fluid from here.

Viscosity requirements for automatic transmission fluids vary with the application. Transmission fluids in automotive applications are usually multi-viscosity, ranging from SAE 0W-20 to 10W-30, and include viscosity index improvers to allow adequate low-temperature performance. Powershift transmission fluids, on the other hand, are often single grade fluids.

ATF Viscosity Characteristics
Product SAE Viscosity
Dexron II & Type F 5W-20
Dexron III, Mercon V & ATF Plus 4 0W-20
Caterpillar Powershift 10W, 30 & 50

If Dexron II is 5w-20, maybe the same viscosity in motor oil is the way to go.

[Mark DiSilvestro]

Well, 5W20 it is.
The reason I decided to check the tranny fluid was yesterday I noticed a bit of whirring noise when idling in neutral. It went away when I depressed the clutch pedal. And I'm planning a 200 mile trip in a couple weeks, so I checked this morning and it was a bit low. Noise seems a bit quieter now with the tranny full. And it's less of a strain to get reverse with the shifter lubed.

Happy Motoring, Mark

[Diesel911]

Originally Posted by Mark DiSilvestro

Well, 5W20 it is.
The reason I decided to check the tranny fluid was yesterday I noticed a bit of whirring noise when idling in neutral. It went away when I depressed the clutch pedal. And I'm planning a 200 mile trip in a couple weeks, so I checked this morning and it was a bit low. Noise seems a bit quieter now with the tranny full. And it's less of a strain to get reverse with the shifter lubed.

Happy Motoring, Mark

When I had the same sound on a Manual Transmission it turned out to be a symptom of an Input Shaft bearing going out.

Safely Jack Up your Car (Ramps are nice for this) and listen with a Mechanics Stethoscope of a Broomstick against the area of the Transmssion you think the sound is coming from to find the locatin of the sound.

[JEBalles]

My '83 with the aluminum case calls for atf.

[Mark DiSilvestro]

Originally Posted by JEBalles

My '83 with the aluminum case calls for atf.

Does anyone have an '82 MT 240D?
So far I'd still like to know why my '82 owner's manual calls for 10W20 engine oil. Maybe I'll ask on the Tech Forum.

Happy Motoring, Mark