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Gearbox Oil Change

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Fri Sep 20 2019, 07:49am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Radox wrote ...

They told me it's not possible to change all the oil at once, but only to "refresh" it with about 3 litres new oil after draining 3 litres from the old stuff. Will this improve my shifting? And must I "refresh" another 3 litres in a few thousand kilometres?

Yes, you replace circa 3 litres, run the car and 'refresh' again, but not in 'thousands' of kilometres but a few hundred. Optimum is 3 times from reports I have seen elsewhere to get the fluid reasonably clean.
1 User said Thank You to C6Dave for this Post :
 Radox (20 September 2019)
Fri Sep 20 2019, 06:29pm
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
Better do a complete gear oil change (and cleaning) at once with a "Motul Evo" gear oil changer...
There are many available now in Germany (https://de.motulevo.com/de/dealers)
Just find a garage which has the special adapter for the Aisin Gearbox.
Sat Sep 21 2019, 10:08pm
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
Just did my gearbox "flush" (3 changes) today, and also drained 3,25 litres so I was a bit suspicious, since only 3 litres are always mentioned in posts.

When I did the level check, gearbox aprox. 60 deg. engine running and "P", 0,25 litres came out, so the box must have been a bit overfilled!

Funny thing is that 3 1-litre bottles of Mobil jws 3309, contains 3,25 litres, since they are a bit over 1 litre each, so maybe the last time the oil was changed, they didn't bother to do the level check, and just pured 3 1-litre bottles in the box after draining.

Between change 1 and 2, I started the engine, and worked through the gears a few times, between change 2 and 3, I went for a 30 miles spin, now time will show if the last uneven pulling at light throttle has disappered.

I've added a few more pictures to clarify how the drain plug works, and location af drain and filler plug.
Picture of filler device, is with airfilter removed, last fill was with airfilter in situ.
After loosening the filler plug use a telescope magnet to lift it out, and for refitting, lower the plug down to the filer hole, and use a wooden stick (something not magnetic) to hold the plug against the hold, while retracting the telescope magnet.
The drain plug was so tight, that my bolt and nut adapter to remove the drain plug twisted, and I had to use an old wheel bolt and a pipe wrench.

1 User said Thank You to Nikolaj for this Post :
 C6Dave (22 September 2019)
Sun Sep 22 2019, 08:09am
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
Thank you for your post and all the pictures!

I would advice to check the temperature of the oil with a Diagbox, it is much more accurate...

When you open the small bolt, a "torrent" has to come out and it should start dripping, then the level is correct

Sun Sep 22 2019, 08:18am
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
Yes diabox might be more accurate, since I just added 3 bottles of 20 deg. varm fluid to the box, and I only measure the gearbox housing, so I might still have a bit to much oil in, but way closer to the right level than before.
I guess I'll find the oil temp menu under the gearbox cpu in the Diabox!?
Sun Sep 22 2019, 09:43am
Joined: Mar 04 2019
Member No: #3847
Location: Halesowen
Just like to mention something that's been omitted here! The level plug does precisely FA if the car is not on even ground! So if you've got it on ramps or jacked, the capacity will be way out!
I measured precisely! At the end of 3 fills I just added about 2 table spoons !
Sun Sep 22 2019, 10:16am
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
I guess I'll find the oil temp menu under the gearbox cpu in the Diabox!?

It is in the "Gear Box Menu", you can also set back the "oil counter" there (to 000001)

How do you open the bolt with the car down on even ground?
Sun Sep 22 2019, 11:47am
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
With suspension in high, I can just get my arm in there, and reach the drain plug, might be a problem if you have short arms...
Sun Sep 22 2019, 05:22pm
Joined: Aug 27 2019
Member No: #4044
Location: Bad Bergzabern
Please report if there is an improvement in gear shifting after your oil change
Mon Sep 23 2019, 05:50pm
Joined: Dec 09 2018
Member No: #3763
Location: Stockdorf
There is definitely an improvement after a complete oil change (with a Motul-Evo machine, including a cleaning formula). The gear changes are much softer, even in cold temperatures...
Mon Sep 23 2019, 06:01pm
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
For the record, oil level was measured on a level garage floor, all wheels on the floor.

Oil temp in Diabox I found under "standard parameters" in gearbox menu, couldn't find it under specific parameters.

There's no radical change yet, change from 2'nd to 3'rd, is still a bit strange, it's like it try to get in 3'rd, then goes back in 2'nd, and then finally gets into 3'rd.

The uneven pulling at no or light acceleration is still there, but not when cold, or after a long drive, so I'm not sure if the gearbox is the only suspect here!?
Medium to hard acceleration is smooth all the time.

I got 2 quotes (around 550 Euro depending on how much oil is needed, up to 20 litres at worst) for flushing the gearbox at garages, and none of them used cleaning fluid because our (AM6) gearbox doesn't have an oilpan like ZF boxes, where you drop the oilpan and change the filter after cleaning.

Anyone tried cleaning fluid on our AM6 box?
Sun Jan 12 2020, 10:48am
Joined: Jul 08 2019
Member No: #3978
Location: Bracknell
Hi all, if like me you are planning to change your gearbox oil by the method of multiple drain and refills, then you can get an economically priced 20L can of Comma ASW @ £136 delivered.

I used AZ Autoparts. Ebay link - Click Here -

I had difficulty removing the central level plug as the Torx location stripped, but managed to get it out:

1. File 2 small flats on the head of the drain plug, approximately diametrically opposed
2. Grip the drain plug in a vice using the 2 flats
3. Using a small cold chisel and hammer, tap the level plug in an anticlockwise direction until it releases
4. I had to do this on opposite sides of the plug, but eventually it undid

Photos included.

Thanks to Hattershaun for the plug and o-ring part numbers.

Interestingly, the level plug I removed had no o-ring. I assume it was the original as it was so corroded, but cannot guarantee.

3 User said Thank You to xantiaboy for this Post :
 321dave (12 January 2020) , Hattershaun (12 January 2020) , cruiserphil (13 January 2020)
Sun Jan 12 2020, 02:35pm
Joined: Sep 20 2016
Member No: #2793
Location: West Mids
Going off at a slight tangent, I wonder if the different gearbox oils (or boxes) themselve are more or less prone to becoming grimy looking ? My C6 has done roundabout 130k, up from 96K when I had it.

I generally do an engine oil change roundabout 6k intervals and after an initial short burst of three gearbox fluid drains, I now do it as the same time as the engine oil ----- and it's still coming out grimy.

By contrast, I have another car with a proper American GM autobox that is on around 96k and when I give that an annual change the fluid comes out as clean as the day it went in. (Good old fashioned Dexron 2.)

1 User said Thank You to onthecut for this Post :
 cruiserphil (13 January 2020)
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