DIY: M-DCT Oil Change/Top Up

[bigjae1976]

I wrote Mike Miller of Bimmer Mag...might be useful...

I just placed my order for a 2011 E90 M3 and plan to make this car a keeper. I've only ordered 1 option to minimize future problems and expenses. That option is the M-DCT due to the requirement for my wife to drive it.

I've heard that the 1,200 mile break in service does not include changing the fluid in the M-DCT gearbox. Is there any value in doing a break in fluid change with the M-DCT? If there is any value in doing a break-in service on the M-DCT, is there any special procedure?

You only selected one option, but that option is the one most likely to maximize future problems and expenses. This is always the case with any BMW transmission that is not the simple basic manual gearbox.

The M-DCT is more automatic transmission than manual gearbox and I really don't know whether it would benefit from a 1,200-mile break-in service. Here is what I do know: Automatics don't benefit from a 1,200-mile break-in service. The M-DCT transmission requires a special hydraulic oil, only available from BMW, that is incredibly expensive and difficult to change. And the BMW dealer will probably fight you tooth and nail if you try to get them to change it ever, much less at 1,200 miles.

[fe55]

I have tried to have the oil in my Transmission a couple of times. Even with the proper computer only about 3.5 l of oil was changed. Most of the oil is located in the cooling lines, radiator and upper parts of the transmission that are not accessable when you drop the oil. So my specialized repair facility has not been able to source any information on changing all the oil even at the proper temperature and equipment.

[aus]

So just change it again in a few thousand miles. It's pretty common with traditional auto tranny's to only get about 1/3 of the oil out each change.

[swamp2]

Update - swapped my fluid:

I found an independent BMW shop to swap my M-DCT fluid. Rumor has it that the units total dry capacity is ~9.5l. They were only about to get between 4-5l out of mine and they claimed they used the computer to cycle the pumps in the transmission (no idea if they actually did). My plan is to swap again in 10k miles or so. Those swaps together will remove about 75% of the total contamination. The proper fluid was not at all tough for them to locate. They also said the fluid that came out looked practically new. Since all it does is bathe the gears that is not too surprising. Sure wish there was a way to get all of the fluid out. That might also require some priming of the various hydraulic systems in the unit, however that capability must be somehow built in. Job took less than 1 hour and I was charged 1 hour of labor.

[elp_jc]

Originally Posted by swamp2

Rumor has it that the units total dry capacity is ~9.5l.

I could bet my house that rumor is wrong man . You'd have all gears submerged in fluid if that was the case. The Getrag M3 manual tranny only holds 2-1/4 after draining it bone dry. The DCT unit is about the same size, and does NOT have a converter, so when fluid doesn't drain out anymore, it's empty as well. And if shop cycled the pump, it pretty much got out everything, although there's very little fluid in the lines and cooler anyway.

I'm sure if you post on the tech section the acutal capacity of the DCT from the service manual, a tech should respond quickly. Even 5L is a lot, so I don't expect any more than that. I'd wait until 20K or so, since that fluid is not cheap, but you did the right thing; fluid is a lot cheaper than a new transmission (or a rebuilt one). By changing it frequently, there's no need to get every drop out IMO, since fluid is still relatively fresh. Cheap insurance. And remember DCTs contaminate fluid with clutch wear, so color alone is not a determining factor of oil condition. You should have taken a sample to have a better idea where you stand. Take care.

[AM150]

I want to say the capacity on the evo DC-SST (dual cutch trans) is something like 8qts. That's a getrag unit also.

[bigjae1976]

Originally Posted by swamp2

Update - swapped my fluid:

I found an independent BMW shop to swap my M-DCT fluid. Rumor has it that the units total dry capacity is ~9.5l. They were only about to get between 4-5l out of mine and they claimed they used the computer to cycle the pumps in the transmission (no idea if they actually did). My plan is to swap again in 10k miles or so. Those swaps together will remove about 75% of the total contamination. The proper fluid was not at all tough for them to locate. They also said the fluid that came out looked practically new. Since all it does is bathe the gears that is not too surprising. Sure wish there was a way to get all of the fluid out. That might also require some priming of the various hydraulic systems in the unit, however that capability must be somehow built in. Job took less than 1 hour and I was charged 1 hour of labor.

You are a brave man! I think I will just do drain out whatever I can every 10k miles and then just refill. Then call it the day!

[swamp2]

^ Read this entire thread. There is this advised "warm refilling" procedure.

Every 10k miles is way too conservative/wasteful/expensive for tranny fluid, DCT or not.

[swamp2]

Originally Posted by elp_jc

I could bet my house that rumor is wrong man .

Could or would?

Originally Posted by elp_jc

You'd have all gears submerged in fluid if that was the case. The Getrag M3 manual tranny only holds 2-1/4 after draining it bone dry. The DCT unit is about the same size, and does NOT have a converter, so when fluid doesn't drain out anymore, it's empty as well. And if shop cycled the pump, it pretty much got out everything, although there's very little fluid in the lines and cooler anyway.

I'm sure if you post on the tech section the acutal capacity of the DCT from the service manual, a tech should respond quickly. Even 5L is a lot, so I don't expect any more than that.

The unit has a lot of lines, both for the controls and cooling all the way to the engine, also the heat exchanger. I don't know if 5 or 10 l sounds right.

Originally Posted by elp_jc

You should have taken a sample to have a better idea where you stand. Take care.

Thought about that but it only would have been more cost, no surprises and nothing that could be done if it indicated a big problem. BMW wouldn't do squat.

[klammer]

Originally Posted by swamp2

Update - swapped my fluid:

I found an independent BMW shop to swap my M-DCT fluid. Rumor has it that the units total dry capacity is ~9.5l. They were only about to get between 4-5l out of mine and they claimed they used the computer to cycle the pumps in the transmission (no idea if they actually did). My plan is to swap again in 10k miles or so. Those swaps together will remove about 75% of the total contamination. The proper fluid was not at all tough for them to locate. They also said the fluid that came out looked practically new. Since all it does is bathe the gears that is not too surprising. Sure wish there was a way to get all of the fluid out. That might also require some priming of the various hydraulic systems in the unit, however that capability must be somehow built in. Job took less than 1 hour and I was charged 1 hour of labor.

great to hear! Please keep us updated as am thinking of doing the same down the road. Quick question, with what regularity should this be done and if i track fairly often (say 15-20x a season) should i step things up? Any help would be appreciated

[elp_jc]

Originally Posted by swamp2

Thought about that but it only would have been more cost, no surprises and nothing that could be done if it indicated a big problem. BMW wouldn't do squat.

I was referring to send it to Blackstone (or other) lab, so you don't change the oil excessively early, due to the high cost of DCT oil. Was just trying to help . Good luck.

[swamp2]

Originally Posted by klammer

great to hear! Please keep us updated as am thinking of doing the same down the road. Quick question, with what regularity should this be done and if i track fairly often (say 15-20x a season) should i step things up? Any help would be appreciated

I think a conservative figure for tranny fluid swap without track use is about 30k. A more reasonable figure is probably 60k. With that much track use I might go with once a year after your season. These are very rough numbers. Check out something like Porsche GT3 MT fluid change intervals just for reference. I'm not saying the trannies are similar but that will be an example of a high performance (and typically run hard) MT. A DCT is basically a MT on the inside.

[swamp2]

Originally Posted by elp_jc

I was referring to send it to Blackstone (or other) lab, so you don't change the oil excessively early, due to the high cost of DCT oil. Was just trying to help . Good luck.

No, it is good advise. No offense. When it is off warranty I will consider Blackstone analysis. Cheers.

[klammer]

Originally Posted by swamp2

I think a conservative figure for tranny fluid swap without track use is about 30k. A more reasonable figure is probably 60k. With that much track use I might go with once a year after your season. These are very rough numbers. Check out something like Porsche GT3 MT fluid change intervals just for reference. I'm not saying the trannies are similar but that will be an example of a high performance (and typically run hard) MT. A DCT is basically a MT on the inside.

thx again Swamp, think might try it after this year as would be about 25k miles and over 30 track days on it, but will definitely look at some other cars as a soft reference. thx again

[bm33]

Hi All,

Advance driver - strong track days - heated up in 110 degree weather three times - still no problems.

Am thinking about changing - Dealer says $45 per quart - 7.5 quarts & 2 hours with a BMW module that activates the pump during the change process

Michael

[aus]

Better prices here: http://www.m3post.com/forums/showthread.php?t=541829

.

[phrogbubbaE92]

Swamp2,

what shop in SD did you go to for your DCT fluid change? Thanks in advance..

[Richard@M-World]

Here are the DCT fluids. Chaning mine this weekend. BTW for some reason my supplier quoted me a lower price per liter for the 1L small bottles compared to the 20L version.

[MiamiM3]

Originally Posted by Richard@M-World

Here are the DCT fluids. Chaning mine this weekend. BTW for some reason my supplier quoted me a lower price per liter for the 1L small bottles compared to the 20L version.

What did it cost per liter? Did you buy it locally or over the internet? When you finish changing the fluid, can you please give a brief write up? I am curious if this is something that can be completed at home or if it requires a GT1 computer to cycle the pumps. Thanks.

[mb1]

Any update on this?

How much did you get out? What was the process?

Originally Posted by Richard@M-World

Here are the DCT fluids. Chaning mine this weekend. BTW for some reason my supplier quoted me a lower price per liter for the 1L small bottles compared to the 20L version.

[Nyobie]

Does anyone know if there's a write-up somewhere that would show a comparison between a conventional automatic transmission versus the DCT regarding the friction elements and 'slip' as the clutches engage?

I'm wondering if the OEM is recommending against changing the DCT fluid because of the significantly decreased friction element wear due to the nature of the design of the DCT. If say, the DCT friction elements wear at 5-10% of the rate of a conventional automatic tranny, perhaps this would correlate to that much of an extension of fluid life?

In any case, those who track their cars are definitely asking more of the DCT than those who don't, so I think it would be interesting to see how much of a difference there is in the particulate matter of the fluid removed from a car that's been tracked 15-20x per year versus one that hasn't been tracked at all with equivalent mileage on the tranny.

[bigjae1976]

I used this DIY on my other M3...Mazda 3...auto tranny. It worked fast and I got to completely flush the tranny fluid.

http://krystmsgarage.com/?p=250

I wonder if the pump on the DCT is accessible and you are able to remove the hoses like the DIY above. Then maybe you could use the DCT pump to drain the old fluid while pumping in new fluid. So the transmission never goes dry and you should be able to do a complete flush.