Which transmission fluid and when to change?

[Waz]

Hi All

I have a 1989 coupe with a 4-speed 722.358 transmission. It has a full MB service history and the last transmission service was in June 2013 (234,000kms) at an indie garage where Castrol Dex II was used. I have been reading a bit about which transmission fluid is right for this gearbox on the American sites but it all apears to have descended into a big online fight. So I am none the wiser. My manual says spec sheet 236.6.

Is it OK to use Dex III in a 722.358? Bearing in mind the licence on Dex III has run out and GM are probably not policing it anymore, what does the "Dex III" label mean any more? Which of the new MB spec sheets is relevant?

The only fluid I can find that refers to sheet 236.6 is the Penrite Classic ATF, which seems to be based on Dex II. This seems to be ideal, but perhaps a more modern fluid would be better? It's hot up here in FNQ and in the summer with the a/c on and sitting in traffic the transmission tunnel does get pretty hot. I can feel it where my toes poke out of my thongs. I have heard that excessive heat is death on transmissions. Although when I drove the car non-stop up between Cairns and Brisbane and it kept a steady normal temperature.

I have also read that some Aussie drivers have said they change their ATF every year due to the heat and it keeps the transmission running in good order. I notice my MB service book suggests changing it every 60k kms in normal use and 30k kms in harsh conditions, but I can't help thinking both are a bit extreme. So what would be a good interval? The car is currently at 246,000km. I don't really mind the expense of changing the fluid, but I don't want to go crazy.

What would be sensible intervals for, say, a full service, and then changing out the fluid only as an interim fluid change (torque converter and all)?

Is there anywhere on the internet where I can find a description of the 722.358 gearbox, or Mercedes gearboxes in general? My searches turn up diagrams or very generic information or parts quotes. I am specifically interested to know how it's cooled. I don't have access to the EPC.

Thanks very much in advance for any advice you guys can give. Great to have an Australian resource for the marque.

Waz

[Ivanerrol]

Here is what the MB specs also say.

http://bevo.mercedes-benz.com/bevoliste ... chbegriff=

http://bevo.mercedes-benz.com/bevoliste ... chbegriff=

or : Change fluid : The factory spec is 30K (miles) with the Dex II fluids available at the time these cars were new Dino fluid is pushing the limits by 30k under normal service, and factory spec is 15k (miles) with severe service (city driving, idling, towing, etc). (and Dex III now).

Redline Synthetic D4 is reputedly /supposed to be very good in those transmissions.

Interesting chart - Look down to middle page for 722.3 and 722.4 transmsissions

http://www.w124performance.com/docs/mb/ ... 1_2013.pdf

[kimrh]

Penrite
The ATF classic for older 4 sp auto's would do fine
Also you could use
ATF DX-III (premium mineral) also specified for the later 722.6 5 speed trans behind the R129 & W140 V8's
Or if wanting to go synthetic
ATF FS (fully synthetic) and ATF MHP (semi synthetic) would be fine as well with the fully synthetic being the preference of choice

If you ring Penrite direct and discuss your in a hot climate i reckon they would point you towards the full synthetic

Redline is a brilliant product (i used in a previous life in my fully worked/Supercharged Commodore with race spec in the auto trans) but it is very expensive.

I fully use all Penrites fluids now as i like the Company and its products and they really cater for the older cars as well as newer and they design their product for our Australian climate (not for cold European ice/snow winter climates). Their Reps in the Penrite Office are great to talk direct with too.

[AMG]

in 722.3 / 722.4 it is best to use a synthetic ATF meeting MB spec (dex 3)
in a 722.5 use genuine MB fluid - it's stupid expensive, but your drain intervals can be prolonged - if you know exactly what you are doing and you get the fluid sampled at regular intervals. The 722.5 is a bit of an achilles heel and needs to be treated a little more gently than other MB transmissions, so let's put it in a special padded cell for the moment...
722.6, personally I'd use the genuine fluid, if I wasn't thrashing the transmission. If I was, then I'd run a high quality synthetic ATF, like Neo Synthetic Hi Vis ATF. Heat is the enemy in these late model transmissions and you need a very high thermal capacity and stability in the fluid. Especially as the latest cars run considerably hotter than older engines, and the trans cooler is situated in the radiator tank.... so heat dissipation in gridlock traffic is not really going to be at it's best.

I do my synATF Fluid changes at every engine oil change. For me, that depends which vehicle. 10-15K usually. I Don't skimp it and be a tightarse about it. new fluid, filter and pan gasket will see your transmission last a whole lot longer than if abused and oil changes delayed until the factory 30K intervals. Forget these "sealed for life" claims as well. trans filter and pan gasket kits are cheap insurance. yes, 8 litres of ATF is not cheap, but if you factor the cost of a rebuild.... it is very cheap indeed.

Remember the old oil ads.... 12 months or 20,000km? well really, that is a pretty good starting point for ALL fluids, with the exception of differential oils (unless you are submerging the diff)

Think about it... Brake fluid... hygroscopic - i.e. absorbs water, and should be changed every 12 months... coolant? yep in this country, 12 months. engine oil? if you're not driving the car, it's still 12 months to prevent it from decomposing, and the same for auto trans or manual gearboxes.... 12 months or 20K.

If you use dino atf, 15K intervals maximum if you drive it enthusiastically. In older transmissions requiring dex 2 specification, you may find a dex 3 fluid to be too slippery. for example, if you have a 4 speed fluid coupling 722.2 You want to run a dex 2 (yes you can still get it easily).

But all the MB 722.3/4/5 automatics were designed to cope with dexron 3 spec fluid. It's just that to coin a phrase.... oils ain't oils.... As kim mentioned, penrites synthetic Dex3 ATF is good value for money and I've run it for a few years, without issues in Stella. Although, she does leak form the front seal a bit, it is not because of the synthetic fluid, it is because the seal needs replacing ;)

If you look after your vehicles with regular routine servicing, then typically It's not the fluid degrading that you generally have to worry about, it's all the friction material dust suspended in the oil that's the problem. Taking care of that is the key to transmission longevity.

[Waz]

Thanks very much guys for all that info!

[Ralf_CT]

in 722.3 / 722.4 it is best to use a synthetic ATF meeting MB spec (dex 3)
in a 722.5 use genuine MB fluid - it's stupid expensive, but your drain intervals can be prolonged - if you know exactly what you are doing and you get the fluid sampled at regular intervals. The 722.5 is a bit of an achilles heel and needs to be treated a little more gently than other MB transmissions, so let's put it in a special padded cell for the moment...
722.6, personally I'd use the genuine fluid, if I wasn't thrashing the transmission. If I was, then I'd run a high quality synthetic ATF, like Neo Synthetic Hi Vis ATF. Heat is the enemy in these late model transmissions and you need a very high thermal capacity and stability in the fluid. Especially as the latest cars run considerably hotter than older engines, and the trans cooler is situated in the radiator tank.... so heat dissipation in gridlock traffic is not really going to be at it's best.

I do my synATF Fluid changes at every engine oil change. For me, that depends which vehicle. 10-15K usually. I Don't skimp it and be a tightarse about it. new fluid, filter and pan gasket will see your transmission last a whole lot longer than if abused and oil changes delayed until the factory 30K intervals. Forget these "sealed for life" claims as well. trans filter and pan gasket kits are cheap insurance. yes, 8 litres of ATF is not cheap, but if you factor the cost of a rebuild.... it is very cheap indeed.

Remember the old oil ads.... 12 months or 20,000km? well really, that is a pretty good starting point for ALL fluids, with the exception of differential oils (unless you are submerging the diff)

Think about it... Brake fluid... hygroscopic - i.e. absorbs water, and should be changed every 12 months... coolant? yep in this country, 12 months. engine oil? if you're not driving the car, it's still 12 months to prevent it from decomposing, and the same for auto trans or manual gearboxes.... 12 months or 20K.

If you use dino atf, 15K intervals maximum if you drive it enthusiastically. In older transmissions requiring dex 2 specification, you may find a dex 3 fluid to be too slippery. for example, if you have a 4 speed fluid coupling 722.2 You want to run a dex 2 (yes you can still get it easily).

But all the MB 722.3/4/5 automatics were designed to cope with dexron 3 spec fluid. It's just that to coin a phrase.... oils ain't oils.... As kim mentioned, penrites synthetic Dex3 ATF is good value for money and I've run it for a few years, without issues in Stella. Although, she does leak form the front seal a bit, it is not because of the synthetic fluid, it is because the seal needs replacing ;)

If you look after your vehicles with regular routine servicing, then typically It's not the fluid degrading that you generally have to worry about, it's all the friction material dust suspended in the oil that's the problem. Taking care of that is the key to transmission longevity.

I've just bought a '92 W124 230E with 202,000km. One of the first things I did was a transmission oil, filter and gasket change. The dealer sold me MB 134, which the forum guys advised against as it was designed for the later 7-speed boxes, not the old 4-speeds. I've since returned it and replaced it with Dexron II. The oil which came out looked good, but the filter and gasket looked like they hadn't been replaced for a while.

[Charlie Buckett]

"[quote="AMG"] if you have a 4 speed fluid coupling 722.2 You want to run a dex 2 (yes you can still get it easily).
Other threads suggest that the dexron III has softners that destroy the bands within a few years, and that dexron 2D is the original and only fluid to use in my 1989 300te (I can't find the transmission number anywhere, but I am guessing its a 723.3 like the original posters.
So my question is, just where can I find this 'easy to get" dexron IID in OZ? I can only find it in England and the postage is a killer.
I have some Penrite DXIII Premium Mineral I was going to put in her until I read about the softners, also it is only specd to 236.5, 236.1,236.10 and 236.11, but not 236.6 as required in the MB manual.
Also, not keen to run synthetic as it was not engineered to do so and the tranny has no leaks at the moment (neither did the engine until I switched from Dino to full synthetic, and then... leaks.)
The fluid looks great and shifts well but I dont know the service history as I have only had her 15 months now, so I would like to change it. A.S.A.P. Cheers all.

[Ivanerrol]

I would not say that the transmission was not designed for synthetic fluid, rather synthetic fluid was not around when the transmission was designed.
If it had been available MB would have recommended it.

MB now recommends 236.14 for these transmissions and in fact if you go to the stealership and by genuine stamped MB stuff it will be 236.14.

A few weeks ago I changed my 722.4 from mineral to synthetic 236.10 (happened to have 20 litres of this). Transmission works fine, shifts well and is very quiet.

On another forum. A member was part of the team which developed 236.14 for M.B. he recommended to put the latest stuff in. The synthetics will help to prolong the life of the transmission.

A lot has changed in 26 years - much for the better.

[Don-vic]

Just adding my uneducated response to this ongoing source of confusion. Following lots of research, I recently changed the ATF of my 1990 300TE from old fluid of unknown age, type or brand to "valvoline Max Life" fully synthetic .
I cannot believe the difference this has made to the cars performance and drivability (smoother changing and holding gears long before changing up under acceleration). At the suggestion of several forum contributors, it is my intention to regularly change the ATF (say yearly or 20K).

[Charlie Buckett]

Thank you for that info,
But I cannot find any reference to MB suggesting it's suitable for specification 236.6 which is what I require."236.14 specs is also backward compatible to the 236.12 and 236.10 specs." but I have not found any suggestion it is comptable to 236.6
It's Pour Point and Viscosity (could not find density specs for the new stuff) are nothing like that of the desired (required) fluid for the 722.3.
Oils aint Oils.
I wont add a link to another forums thread as I don't know if that is kosha here. but I will refer to it.
I am concerned about the viscosity of the 236.14. It is a lot thinner, in auto transmission, "you need an oil with a defined friction and you cant't use a 'better' one" or you will destroy break bands etc. (Although I am sure it will do the job well for 'some' time).
I've heard that "switching fluid this late in the game can strip the clutch material off the clutches" and to only swap to synthetic after a rebuild.
"For right shifting, you need exactly the right ATF." and in my case that is Dexron IID, I am hoping to find a recommended oil/fluid with the "right liquidness, comprehensive restistence, friction coefficent," I guess what I am hoping to find is some old stock Dex IID which 'AMG' posted as being still easy to get. "Yo AMG! are you still out there?".Where is it easy to get in OZ?
Otherwise I am leaning toward the Penrite Classic? but need to do more research.
I'd rather replace the right fluid every year than put the wrong viscosity/density/temp synthetic in thinking it will last longer.
Yes, Oil has come a long way, and so has fuel, but I wouldn't put the latest lead free additive filled petrol for todays cars in something like an unmodified 1969 911 Porsche engine (or an old Datsun engine etc) unless I wanted to kill it? Similarly the transmission for the w124 was built to very specific specifications that dont suit all the softners and additives etc of newer fluids. Yep the new thin fluidy stuff for 7 speed boxes will work just fine in the old girl for a while, but how long is that while?
I really appreciate all contributions. Thanks.

[Charlie Buckett]

Yay !!!!! I think this is the answer for me http://www.penriteoil.com.au/products.p ... oducts=713 (I really, honestly hope everyone does well with their synthetics but I just wanted to be extra careful and stay as close to the fluid the transmission was designed for.)
Thank you Penrite, now I just hope they still make it. Anyone know of a stockist?

Penrite Classic ATF
Typical Data
Colour Red
Density at 15°C, kg/L 0.848
Viscosity, Kinematic, cSt
at 40°C 38.0
at 100°C 7.9
Viscosity Index 186
Boron, Mass % 0.013
Flash Point, °C 192

Dex IID (Original Transmission Fluid for w124)
Density at 15°C 0.875
Color Red
Viscosity at 100°C 7,5 cSt
Viscosity at 40°C 37,0 cSt
Viscosity index Min. 150
Flash point 190°C
Pour point ­35° C

[Ivanerrol]

Three weeks after changing the fluid and filter the transmission has failed :whistle:
It looks like the B2 band.

I had hoped that pulling out the synthetic stuff and going back to mineral may give the transmission a nudge however when removing the pan there was too much dust and some metal filings.

The transmission had previously been filled with synthetic. 60,000 k's ago.

I couldn't find any Penrite mineral Dex11D down at Supercheap only Penrite mineral Dex3

[Charlie Buckett]

Really sorry to here about your transmission. Were there any symptoms leading up to its demise?
Penrite Classic IID can either be purchased online through Motofluid here http://motofluid.com/classic-atf/
Or you can order through Autobahn but they charge $10 Freight?
I don't think putting in the correct oil now will undo anything alone.
There are some quick fixes that may get you a few extra miles.
It is very irresponsible for people to have suggested placing fluids in a transmission with many hundreds of thousands of klms on it that are so far removed from the specified fluids that the transmission is designed to cope with.
There is a particular post on this thread that is wrong on so many levels it makes me angry that he has given advice.
Good luck.

[Charlie Buckett]

Oh, actaully Ivanerrol, I just noticed that it was actually your own post in reply to mine that got my goat.
"I would not say that the transmission was not designed for synthetic fluid, rather synthetic fluid was not around when the transmission was designed.If it had been available MB would have recommended it.". I don't know where to start with the logic of this. Synthetic was not around, and hence the design of the tranny was for thicker fluid without all the softners that wrecked your transmission. If sythetic had been around back then, then yes they would have recommended it because they would have designed the tranny and its materials differently.
"MB now recommends 236.14 for these transmissions." In reference to my previous post in reply to yours. This is just not true. Mercedes recommends "236.14 backward compatible to the 236.12 and 236.10 specs." but I have not found any suggestion anywhere of M.B saying it is comptable to 236.6 for your old transmission.
"...in fact if you go to the stealership and by genuine stamped MB stuff it will be 236.14"
Of course it will, they do not make/stock fluid for 30 year old transmissions. They will sell you the only product they have at a premium profit.
"On another forum. A member was part of the team which developed 236.14 for M.B. he recommended to put the latest stuff in. The synthetics will help to prolong the life of the transmission." I read that thread and this 'guy' was referred to in a vague quote from a third person, with no clarification if he was refering to a rebuilt gearbox or one with many miles on it. Nonetheless it is absurd to think the latest runny fluid for a 7 speed and filled with additives and softeners that can be harsh on the old bands is compatible with a thirty odd year old box designed for completely different specs. With that thinking it should be o.k to run the new boxes on the old spec fluid, I'm sure it will work well for a while.
"A lot has changed in 26 years - much for the better." I addressed this in my first reply to your post. My neighbour burnt holes in the valves of his V.W because he was too stingy to purchase the lead additive for his fuel and just ran the much 'Better' new fuel for newer disigned engines.
I am very sorry your transmission died. I just hope you did not influence too many other people with your previous advice.
'

[merc-304]

https://autoexpert.com.au/posts/the-tru ... ealed-ones