2009 C5 2.0 HDi Auto - should I change the auto box fluid?

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2009 C5 2.0 HDi Auto - should I change the auto box fluid?

Post by steveclv »

So I recently purchased my 2009 tourer here in France with a good service history but no evidence of the AM6 auto box ever having had a fluid change. The car runs great and the box seems generally smooth although a little jerky at town speeds which made me thing that the torque converter isn't working as smoothly as it should. Might be off the mark though.
The car has 250,000km (155,000 miles) but of course the box is meant to be sealed for life but I have read that some people have done fluid changes.
Do you think a fluid change would be worth the cost - I don't yet have Diagbox as was let down by the Aliexpress seller so not something I can do myself yet.
Do you think it would help the jerky low speed on/off light throttle behaviour or is that normal for the car?
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Re: 2009 C5 2.0 HDi Auto - should I change the auto box fluid?

Post by GiveMeABreak »

To be honest it really should of been done a few times by now...

You can't fully change the oil out in one go as about 4 litres out of the 7 litres will remain in the torque converter, so often people tend to change 3 litres, top up and run it for a month or so, then repeat and repeat again in another month to approximate as near a full change as possible.

You need the diagnostic tool to monitor the gearbox oil temperature as it has to be at the correct temperature before draining, and then to reset the oil counter afterwards.

Put it this way it can't do any harm.
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Re: 2009 C5 2.0 HDi Auto - should I change the auto box fluid?

Post by moizeau »

My box had done 160k miles when I bought the car. Oil never changed but it spent it's life on the motorway. I've done multiple part changes. It's now done 225k miles. When the car is cold it is very smooth, when it's up to temperature it 'sometimes' has a jerk between 1st and 2nd and the other way round. It also has an occasional flare between 5th and 6th. It started doing this AFTER I did the first oil change using the correct spec Total oil. I've since used Mannol, bought by the 20l tubs at a fraction of the price from Germany. It hasn't got any worse. The jerking and flaring is due to the electro-solenoids being worn. I've read that the gearbox temp is roughly 10 degrees lower than coolant temp, though I've never verified this. The first time you do it it is a bit unnerving watching oil run out whilst the engine is running!
Before you do the change go your local PSA dealer and get replacement O rings for the drain/level plug as well as a new level plug screw. The filler under the battery is factory torqued to FT N/M so get a good quality torx bit. I think I posted the part numbers in the gearbox oil change thread.
Notice the BX is still top the list but sadly gone
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Re: 2009 C5 2.0 HDi Auto - should I change the auto box fluid?

Post by Sloppysod »

Another tip.
Connect a length of 13mm (ish) tube (300mm long) to the bottom of a funnel, then on other end a piece of 13mm diameter tube about 50mm long, use a screw type clip and it stops in going into the gearbox.
This will make it easier to top up the fluid without spilling it, the 13mm tube fits nicely in the filler hole close to the battery tray.
And yes, VERY unnerving watching oil poor from a running gearbox😱

As for the not so smooth gear changes, possibly the valve block, which can be replaced quite easily with the gearbox still in the car.
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Major interventions
C5 Steering rack @ 58,000 mi
4 discs & Pads @ 63,585 mi
2 (AM6) oil exchanges @ 58,876 & 72,378 mi