Automatic transmission 722.9 oil.

[HOV]

I did an oil change on my automatic gearbox 722.9, the car comes with start-stop and the VIN decoder shows the fluid to be the Blue type. However, the fluid that came out was redish (burnt) colour and the pan had quite a bit of sludge but no metal filings.

I drained the converter but I didn't flush the cooler, the fluid coming out of the pan after draining at 45C was already looking darker but I only had 10 litres of transmission fluid and the car was booked for an MOT the next day so I had to pack it up as it was.

The car actually feels a lot nimbler and the gearbox seems to be working fine but there are a couple of things niggling me.

Do any of you know if there's an aftermarket transmission fluid for this gearbox that it's red in colour and the previous garage might have used? Or has the car been running on the wrong fluid for a long-long time?

I might end up just doing another fluid change but it's a pain the backside when you don't have a car lift, that's even before you take into account the cost of the fluid and all the parts!

 

[FlorinM]

Even if they used aftermarket transmission fluid, it should still have the same color and specification as the fluid you used, so it sounds like the wrong stuff was used.

Not sure if it's worth doing another change right now, maybe do it in 2 years instead of the standard 5 year interval just for peace of mind.

 

[markjay]

The 7G transmission needs ATF to MB Specsheet 326.14 (Red, if buying genuine MB ATF).

The 7G+ transmission needs ATF to MB Specsheet 326.15 (Blue, if buying genuine MB ATF).

One common aftermarket ATF is Fuchs Titan ATF, and they use the same colour coding as MB (326.14 Red, 326.25 Blue).

Unfortunately, I don't know what colour dye other manufacturers might be using.

Note that MB326.15 is not downwards compatible with previous MB-ATF-Specifications.

 

[HOV]

Even if they used aftermarket transmission fluid, it should still have the same color and specification as the fluid you used, so it sounds like the wrong stuff was used.

Not sure if it's worth doing another change right now, maybe do it in 2 years instead of the standard 5 year interval just for peace of mind.

Yeah, I am pretty sure the wrong fluid was used, I have seen a big difference in gear changes, fuel economy, power delivery and the general behaviour of the gearbox. For example, it had this quirkiness of hesitating when accelerating after a tight right hand turn (like small roundabouts), that it's gone now.

The 7G transmission needs ATF to MB Specsheet 326.14 (Red, if buying genuine MB ATF).

The 7G+ transmission needs ATF to MB Specsheet 326.15 (Blue, if buying genuine MB ATF).

One common aftermarket ATF is Fuchs Titan ATF, and they use the same colour coding as MB (326.14 Red, 326.25 Blue).

Unfortunately, I don't know what colour dye other manufacturers might be using.

Note that MB326.15 is not downwards compatible with previous MB-ATF-Specifications.

Thanks for the info, I think I know where the mistake was made. My oil pan has dimples instead of ovals. As you might know, it's generally accepted that if the pan has dimples, it takes red fluid.

On a closer inspection, my car has the additional electric pump that only the 7G Tronic - plus has, to assist with the start-stop. Also, the VIN code clearly states code A89, which is reduced friction gearbox and obviously the car does indeed have start-stop.

I am pretty sure that mixing the fluids shouldn't be much of a problem in my case, because my gearbox it's designed to take the low viscosity/reduced friction fluid and both fluids are 80-90% Petroleum C20-50 base, just with different additives.

However, I am going to do a fluid change and cooler flush as soon as I can.

Moral of the story. Don't just go by dimples or not dimples in the pan!

Thanks guys, mistery solved!

Ps. That fluid has been there for a very long time. I would say, at least 60-70k miles and there seems to be no permanent damage done, fingers crossed.

MSDS for both types of ATF can be found here: recommendations

 

[DSM10000]

Even if they used aftermarket transmission fluid, it should still have the same color and specification as the fluid you used, so it sounds like the wrong stuff was used.

Not sure if it's worth doing another change right now, maybe do it in 2 years instead of the standard 5 year interval just for peace of mind.

If it is wrong fluid what possible reason could there be for running with it for 2 more years? What peace of mind does that bring?

 

[neilrr]

I agree. If it is the wrong fluid I'd change it IMMEDIATELY.

 

[HOV]

I agree. If it is the wrong fluid I'd change it IMMEDIATELY.

Looking at the MSDS, it looks like this way around shouldn't be that much of a problem, both formulations use the same base but the new ATF has different friction modifiers and additional solvents.

If it was the other way around, i/e adding blue ATF to the old gearbox, that I think it would be a lot more urgent to get the right fluid in.

Nevertheless, I have already ordered the new filter kit and I will pick up the new fluid on Tuesday.

As a side point, I found the original MB fluid to be either on par or even cheaper than other brands (£50ish per 5Lt), go figure!

 

[alabbasi]

Shell ATF-134 is the most affordable but anything that meets the 236.12 standard should be fine.

 

[markjay]

Shell ATF-134 is the most affordable but anything that meets the 236.12 standard should be fine.

That's for the 5g I think?

 

[HOV]

That's for the 5g I think?

Yeah, that's for 5g and earlier 7g.

The one for 7g plus it's 134FE

 

[alabbasi]

That's for the 5g I think?

236.10 is for the 5G .12 and above is for the 7G. ATF-134 now meets .14

 

[HOV]

236.10 is for the 5G .12 and above is for the 7G. ATF-134 now meets .14

You need .15 for the 7G plus with start-stop. ATF-134 it's red, ATF-134FE it's blue.

Edited to add. 236.15 fluid is not backwards compatible with the previous 7G gearboxes because the new ones with start-stop are built with different tolerances to minimise internal leaking, they have a new torque converter and they even designed a new flow path to the clutch plate.

That's why they changed the fluid colour, to help differentiate between the new and the old.

 

[alabbasi]

You need .15 for the 7G plus with start-stop. ATF-134 it's red, ATF-134FE it's blue.

Fair enough, my newest MB is a 2005 and it's an AMG so it has a 722.6, I don't plan on buying anything newer so I stand corrected.

 

[HOV]

Fair enough, my newest MB is a 2005 and it's an AMG so it has a 722.6, I don't plan on buying anything newer so I stand corrected.

Never worry, it's a literal nightmare to figure out which fluid goes where. It doesn't help that it seems, some of the new gearboxes were filled with red fluid at the factory during the transition period.