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Old 10-06-2011, 08:45 PM
tempestv8 tempestv8 is offline
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Location: Melbourne, Australia
Join Date: Oct 2005
Posts: 241
Mein Auto: '03 530i Touring & '03 X3
Originally Posted by madurodave View Post
Was the AT fluid a big job? I believe you have to loosen the pan, let the fluid come out, remove pan, clean any gasket material off and wipe down, replace filter, reattach pan (what torque value?), then fill?

Hopefully not too bad.


I've responded to your query from the transfer case fluid thread using this pre existing automatic transmission fluid change thread, so as not to dilute (no pun intended) the content of the two separate subject threads.

I didn't bother to undo the pan or replace the original filter. In my past experience with auto gearboxes where I did undo pans, replace pan gasket and fluid filter, wipe down any swarf that may have settled on the bottom of the pan or collected around the magnet, etc, is that it's mostly unnecessary.

I've never found any big chunks of friction pad material in the filters, and if there were, the transmission is beyond just a fluid change anyway, as the friction material only breaks away when severely overheated.

My personal opinion is that a simple fluid drain and refill with fresh fluid of the correct specification is sufficient to extend the longevity of the automatic transmission. Removing the pan/filter only increases the risk of introducing foreign materials into the gearbox, especially if the immediate area surrounding the gearbox is dirty (but who takes an X3 offroad anyway? ) Or possibly risk damaging the threads on the sump pan bolts by over torquing.

So I've simply renewed the fluid. Easy and cheap job and most importantly, significantly lower risk of damaging the gearbox.

My biggest challenge was to top up the fluid using my home mechanic style oil syringe, because the twin exhaust pipes run alongside the transmission, very near the fill plug location. With the engine running to warm up the fluid in the gearbox to achieve proper fill level, the exhaust pipes get quite hot.... Since I don't have asbestos hands, I had to endure some pain as I hand threaded the fill plug back on. Ouch!

I checked the amount of old fluid that I got out and it was around 5.5 litres, according to my oil catch pan. This is roughly the same amount of fresh new fluid that I was able to put back into the gearbox, so I think the fluid level inside the gearbox is about right.

I've driven the car around now for a week, and seems like the fluid change has had no adverse effects to the shift quality of the gearbox, which was very good to begin with.

I would highly recommend changing the auto trans fluid, especially after I saw just how black the old fluid was. It was truly in a disgraceful state - black like engine oil, but being auto trans fluid, it doesn't stain. The new Dexron VI fluid was a dark red colour.

Last edited by tempestv8; 10-06-2011 at 11:39 PM. Reason: Adding more details.
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