Changing the Rear Differential / Transaxle Fluid and Filter on an Aston Martin DB9

Draining the Rear Differential Oil on an Aston Martin DB9
In the first post I explained how to drain the oil

This is the second part of my post on Changing the Rear Differential / Transaxle Fluid and Filter on a DB9.  You should really check out my previous post and video on draining the rear differential fluid first as this is a continuation of that process (you can find it here).

We left off with the car in the air, rear under tray removed, drain & fill plugs removed, oil drained and filter removed.   Time to get on with putting it back together!


Gear Oil Pump
Gear Oil Pump

Tools needed (in addition to those listed in the first part of the series) include:

  • Torque wrench
  • Gear Oil Pump (that you can attach directly to the 1 liter bottles available for about $11 online)

New Parts

Rear Differential Fluid Change Parts for an Aston Martin DB9You’ll also need your replacement parts and fluids, namely:

  • 2 liters of Aston Martin approved Shell Spirax S6 AXME 75W-90 lubricant
  • 2 new copper gaskets for the drain and fill plugs
  • new filter (optional if you opted to clean the old one thoroughly)
    • Aston Martin P/N 4G43-27-10490 and goes for about $100 online
  • new O-ring for the filter (optional if your old one is in good condition, but how can you tell until its leaking – so I recommend splurging a couple of bucks on a new one)
    • Aston Martin P/N 4G43-27-10491 for about $2 online

Cleaning of the old parts

Do your best to thoroughly cleanup the old parts you intend to reuse, including:

Aston Martin Rear Differential Service Parts
Cleaned up and ready to install

Drain Plug – Note that it has a magnet built into it to capture fine metal particles.  You should check this after it you removed it.  It’s normal to find a very small amount of metallic sludge on the magnet – this is regular wear and tear to the gears.  If you find larger particle sizes or a LOT of metal, you might want to take some photos and get in touch with your dealer as you have a bigger problem brewing.  After you’ve had a look at it, just give it  a simple cleanup with a rag and some cleaning solvent.

Fill Plug – just give it  a simple cleanup with a rag and some cleaning solvent.

Filter – If you plan to replace it, you can just toss the old one.  If you want to reuse it, you’ll need to clean it out using solvent.  Cleaning the outside of the screen is only part of the process, be sure to clean the inside and get all the accumulated debris out of the inside by rinsing through the passages.

O-ring for filter – If you plan to replace it just toss it.  If you want to reuse it you can carefully pryse the old one off the filter while its being cleaned.  Check it for any signs of flattening or cracking.  If you spot ANY potential imperfection, just opt to replace it.  If it’s in good condition just wipe it down (no solvents – they may make it swell).


Start by fitting a new O-ring to the filter.  Apply a little bit of the new lubricant to it to make this easier.  Install the filter into the differential housing and replace the two 8mm bolts, torqueing them to 5 Nm (snug).

Install the cleaned drain plug along with a new copper gasket.  Use the 14mm hex socket and torque to 49 Nm (36 ft-lbs).

Now it’s time to add the lubricant.  Position your drain pan below the fill port.  Connect your Gear Oil Pump to the first bottle of gear oil and run the tube up into the fill hole.  Manually pump in the first liter, and then change to the second bottle.   Fill more slowly this time watching for the first signs of oil dribbling back out the fill hole.  You need to add approximately 1.7 liters of fluid.   Once the oil is dribbling out, remove your fill tube and allow it to continue to dribbling out until it slows to just barely a drip (this way you can be sure it’s not overfilled).

After it’s slowed to a drip, it’s now time to install the Fill Plug along with a new Copper Gasket.   Use your 22mm socket and torque the plug to 49Nm (36 ft-lbs).  Be especially careful not to damage the fins on the oil cooler that is right beside this area.

Meticulously wipe down the outside of the differential housing to remove any traces of old fluid or new drippings.  You want to do this now so you can spot a new leak of any kind (besides, you want your Aston looking sharp!).

Drain all the used fluids from your drain pan into an old container like a used milk jug and then take it to a proper disposal center like a local auto shop for recycling (thanks Pep-Boys!).  Take all your oily rags, gloves, paper towels and cardboard and dispose of those in the trash.  They stink (like the gear oil) and you don’t want to keep oily rags in your garage for the fire hazard.

Here is a short video on the process I followed:

At this point all you have left to do is replace the rear under tray and lower the car back to the ground if that was all you were doing.


26 thoughts on “Changing the Rear Differential / Transaxle Fluid and Filter on an Aston Martin DB9

  1. Pingback: Installing the Rear Under Tray on an Aston Martin DB9 | Aston 1936

  2. jacob backhausen

    Hi, I love your web block. I live in dubai and own a 2007 DB9. I have a tiny leak in the rear left axle output seal. I will receive the parts soon from england and do the repair myself. Just wanted to let you know that I’ve had good inspiration of looking through your posts. Thanks


    1. Nice to hear you like it. I am the same way, if I can get a sense from someone else a project is possible, I am more confident about attempting it. That’s why I started this blog. I hope things go well with the axle seal leak. I hear Dubai is tough on cars due to the sand/grit in the air.


      1. jacob backhausen

        Hi Steve. Do you have an email adr. so I can give you a PM. I have a few very easy but very important steps for you, to improve your Webpage to pop up high on the search result list.
        Here is mine.
        Rgs. jacob


  3. Jonathan Cook

    Hi Steve – this is Jonathan Cook I live in between the UK and India – Goa 🙂 Just a quick note to say a Hugh thanks for your articles. They are simply the best – I do a lot of my own servicing as to be honest the main dealer is not that good and far too expensive etc etc. I just did the diff oil as was experiencing the classic symptoms – yes its now sorted – your articles are really first class. Totally invaluable – so if you are ever in the UK or Goa then please get in touch as would definitely like to meet up as owe you a few beers to say the least – all the best for now – oh my e mail is


  4. Donny Crayne

    Where do you buy your Aston Martin parts? I need to change my differential fluid and am wondering if you have a good source for parts.


    1. Hi Donny, If you are anywhere but in the US, I would suggest you reach out to Rob Sims at HWM England. He’s looked after me well. Email him what you are looking for at Tell him I sent you.

      If you are in the US, Aston Martin has recently decreed that no UK dealer is allowed to ship here anymore (undercutting the overpriced parts from the US dealers), so you are left to contact a US dealer, or perhaps to reach out to a parts specialist in the UK that isn’t a dealer (and isn’t bound by the same Aston Martin contract). Try reaching out to Specialist Motors Ltd. in England and mention I sent you. If you are just getting a few O-rings and copper drain plug seals, the US dealers should be fine. If you are spending some real money on parts, it might be worth looking to the UK.

      Another US source might be Run by an avid Aston Martin enthusiast, redpants has an online store as well.

      You can get your rear differential fluid easily in the US from The Castrol fluid specified is only available in the UK, but the US dealers use Castrol Syntrax Limited Slip 75W-90

      Let me know who you end up using for parts and how it goes. Good luck!


  5. Donny Crayne

    I got my parts from the Aston dealer in Nashville, TN. I did not buy a new filter but just cleaned the existing one in my parts cleaner and it was very easy and cleaned quickly. The fluid change took about 20 miles for differential to smooth out. As long as I had it on jack stands I cleaned the wheels, wheel wells, replaced the outdated hard tires and bled the brakes. Good times in the garage. Thanks again for the time you invest in this site.


  6. Sultan

    Steve hi hope your well, I just wanted to poke your mind.i have 2005 Aston Martin db9 coupe and it’s never really given me any problems, but just driving the other day and suddenly the car decided to go out off drive mode in to netrol. After few seconds off me pressing D it eventually went back in to drive mode. All is fine again,but since then it has happen 3 more times.Any thoughts?


    1. Hi Sultan. That’s a strange and potentially scary problem. That hasn’t happened in my car, and I am not sure what would cause it to change into neutral by itself. Maybe a fault in the switch wiring, something that’s causing the same effect as pushing the Neutral button? Or maybe the transmission is doing it deliberately to save itself. Not sure. Let me know if you figure it out.


  7. Nick Williams

    Hi Steve,

    Would you happen to have any extra copper gaskets and/or o-rings that you’d like to sell? My nearest dealer is a couple hours away and I thought these came in 10-packs?


    Nick Williams


  8. Scott

    Hi Steve,

    Just wanted to let you know your videos are tremendously helpful. Just finished replacing my differential oil (2006 DB9 coupe). Next to do: upper control arms — you can probably imagine how much they squeak up here in Western Canada!


    1. Glad the videos and articles are helping. Western Canada – Vancouver, Calgary or Edmonton? I’m an Edmontonian originally. I’d be terrified to drive a DB9 in Alberta most of the year – odds of a rock popping up and cracking the front windshield.


      1. Scott

        Far West — Vancouver.

        I’m able to daily drive the car about 10 months out of the year. It hibernates in the garage when there’s salt or snow on the roads.


  9. NoRush

    Shell Spirax S6 AXME update to S6 AXRME

    Hi Steve,
    Just sharing that Shell updated the diff oil spec on the Spirax S6 AXME 75W-90 to Spirax S6 AXRME 75W-90.
    I couldn’t find that update noted anywhere, so just putting it on here for reference.

    Request:Hello Shell customer service,
    I have a 2005 Aston Martin DB9 automatic transmission car that states to use Shell Spirax S6 AXME 75w/90 for the differential oil. I ordered that product from Overlake Oil Inc and they sent Shell Spirax S6 AXRME 75w/90 instead. Are the two products interchangeable when changing the differential gear oil? Please advise.

    Please find below the information regarding your enquiry send to technical helpdesk.

    Case No: 00072537
    Enquiry: Shell Spirax S6 question for Aston Martin DB9 automatic differential use AXME vs AXRME

    Good morning,
    The Spirax S6 AXME 75W-90 had been withdraw and the Spirax S6 AXRME 75W-90 is the direct replacement.

    Best regards,
    Shell Canada Technical Support
    Technical data sheets and SDS may be found at:


  10. Adrien Canu

    Hi Steve, first of all, a huge thank for this blog, a bible for all DB9’s DIY guys.
    What do you think about Castrol Syntrax limited slip 75w140, which is used in many limited slip differentials (espencially by Bmw Motorsport users) ?
    On my DB9, the differential is noisy in small manoeuvres (like smalls roundabout), I think mainly when the oil is cold. It reminds me of my former Bmw M3 e46, which is known for its fragile differential.
    As this oil is recommended to resolve such problems, I was thinking of using it for my DB9.

    Friendly greetings from south of France,

    PS : Have you made the draining of your DB9’s transmission ?


    1. Hi Adrien. I’m using the Castrol Syntrax 75W-90 in my car. I can’t really say what the results will be upping the viscosity to 140. Its unusual I think to hear your diff, and I’d be worried about what was causing that. I presume you’ve already changed your diff fluid, and cleaned the screen/filter. There is a diff oil cooler, so I’m not sure if the thicker fluid would have trouble flowing through it, but maybe it would be fine.


  11. Stuart

    Hi Steve, As written to you directly, I wanted to repeat my thanks to you for such a comprehensive website and accompanying videos about all things DB9. Its a great help to me and by the looks of it hundreds of other enthusiast who are interested in maintaining their vehicles economically.

    I have not have my DB9 very long but have already found lots of your posts and videos extremely useful, I will be tackling some of the easier jobs such as pollen filters, headlining and diff oil to ease myself into getting to know the car.

    Re the Diff oil procedure you detail, My local AM dealer advised adding ‘Kendal Oil additive’ to the fresh oil to avoid potential noises which some people have reported and I know can be an issue on other makes. You don’t refer to it in your original instruction so I wondered if you or other readers had heard of this?


  12. I apologise if this is not allowed, please remove if necessary.

    I run the business “Lube Finder” in the UK and we stock Shell Spirax S6 AXME 75W-90 in 1 Litre bottles and dispatch worldwide.

    You can find and order from here if you are having trouble locating a source for 1L bottles close by.

    We are still receiving S6 AXME 75W-90 stock direct from Shell in the UK so not sure when AXRME will be rolled out here, but we’ll switch when it is.

    Best wishes

    Graham Wharton


    1. kapium

      Hi All,

      The differential O-ring is 20.63 x 2.62mm. If you’d like to just buy one instead of paying AM handsomely, use that size. If you’re in the US the following O-ring is a replacement from in Viton: 2063262MMV. The one I found fitted to my DB9 was Buna (nitrile) so this one is superior in a static application like this. They also carry a suitable throttle body O-ring in Viton under SKU: 7587262MMV. Viton is wholly unnecessary in that application but they do not carry a buna o-ring the same size.

      Also, the copper crush washer is 22x28x1.5mm. This part at Amazon fits the bill nicely:

      I’m not against using OEM parts, in fact, I prefer them. But, when the OEM part is a stock item like these there is no need to pay a 1000% markup, IMO.

      Happy motoring!


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