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DIY - Mazda6 GH Series 1 5spd Auto Transmission Service

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I've been a member on NS for a while though I haven't contributed anything to date in the Mazda forums, but have noticed a distinct lack of DIY info pertaining to this car .


This is our 1st Mazda6 and the only one I've had to work on as my partner had a number of Mazda3's as company cars over the years (we had such a good run that when it came time to buy her a car it was a no brainer that we'd get another Mazda and that's coming from a Nissan guy).


I've always done my own servicing and repairs (albeit mostly, Nissan, Holden and Ford's) and have found that many people are reluctant to either work on these cars or talk about what they've done and how they went about it so I'm going to share some recent work in the hope it helps somebody out.


So far I've only done basic things, change the oil (you need a special tool or you can mock one up) checking fluids, new air filter, new cabin aircon filter etc. The car has now done 85ks and I thought it was time to see how the auto was travelling (we bought it second hand at 73ks with a full history).


My fluid was noticeably darker/greyish and had a distinct odour when compared to the new red fluid. I had an auto trans place confirm he felt it should be changed and he supplied me with the filter/gasket kit.


This process took me about 4.5hrs but I was very slow and methodical and have no doubt it could be done faster now I know what to do and where. A basic drain and fill would be about an hour I'd say.


There's a few ways you can go about this and you could certainly do it a touch cheaper/faster than I did, but this way ensured a larger volume of clean fluid went in as I drained it twice and I'd be reluctant to only drain it once given what I saw.


Here's what you'll need.


Filter/Gasket Kit - $28 from local Auto Trans Shop

Trans Oil - $65ea ATF M-V: The only fluid I could find that specifically listed M-V was Nulon (http://www.nulon.com...smission_Fluid/


The car holds a touch over 8L and it comes in 4L bottles, so I bought 2 but you could get away with 4L, more on that later.

Jack stands, you could get away with just 2.

A good jack

A small 10mm socket and by small I mean 1/4" drive or something similar, there's no space for 1/2" stuff here.

You will likely need a suitable knuckle to match your socket set or a flex bit for a drill with a socket attachment, more on that later.

8m allen key.

Good lighting/lead light.

Ample workspace and a level floor.

Latext gloves to protect your hands.

Plenty of rags and also some rags/covers for your quarter panels/bumper and to place over the auto dipstick area when filling.

A range of funnels.

A sharp chisel or something similar to pry the pan off if you're doing a filter replacement also.

Suitable tools/material to clean the gasket surfaces of the pan.

Some low/medium strength Loctite/thread locker for the pan bolts.

A good oil pan.



Here's how I went about it.


Draining/Flushing/Filter Replacement

- Either go for a drive to warm the car up or start it and let it idle while you do the next step.

- Jack at least the front of the car up (I used the subframe mounting points so I could easily place a jack stand on the designated jacking spot for the car) I opted to jack the whole car up (the rear can be jacked from a solid point just in front of the split in the exhaust system - in front being towards the front of the car).

- Use the 10mm socket to remove the screws holding the undertray on.

- If you drove the car, proceed to next step, if you didn't now is the time to give the car some revs and shift it through all the gears to get the auto nice and warm, keep yourself and anyone else clear of the front wheels - it doesn't take much to warm it up. Turn it off.

- Use the 8mm Allen key to remove the drain plug and stay well clear of the fluid as it's not good for you. Approx 3L will come out (I drained my fluid into containers of known size to keep track of how much was coming out).If you are not replacing the filter or looking to flush the system move on to the refill portion after refitting the drain plug. Otherwise continue.

- Refit the drain plug. Proceed to Filling section and then return to this section if you're going to replace the filter/and drain/flush the trans twice.

- Remove the drain plug and let another 3L or so drain out, at this point you should see it has a very slightly reddish tinge and the smell may have changed but it's still quite grey. Refit the drain plug.

- Use your 10mm socket and various attachments to remove the large number of bolts holding the pan on, the passenger side bolts are the hardest to get to so start with those to make sure you can get at them with the tools you have, you could also consider removing a small piece of plastic trim from the passenger side wheel arch but I didn't need to do this.

- Using a sharp chisel - the correct way as not to damage the surfaces - gently pry off the pan working around the edge evenly, the old liquid sealant will hold in place so it will come away gradually, be careful here as the metal is quite soft.

- When you have the pan free, keep it level as there'll be another 500ml-1L of fluid in the pan.

- Remove the black plastic cartridge filter and replace, be careful of extra fluid that will pour out of this also. There's a small black sensor clipped into the filter, simply wiggle it free gently first.

- Clean out the pan thoroughly and clean up the mounting surface, I did not remove every single bit of sealant but made sure there was nothing that would foul the new gasket.

- Pay particular attention to the donut shaped magnet in the pan, clean this but examine the contents of what you remove, the metal should be very fine, like a silt, any larger chunks could mean premature wear has occurred.

- Clean the bottom of the transmission mounting surface so the gasket will not be impeded.

- Ensure that there's no old sealant either in the pan or up on the inside of the transmission.

- Refit the pan and the new gasket (mine was cork but they can be other materials also).

- I opted to add a drop of medium (blue) Loctite to each bolt which added time and getting the passenger side bolts in and tightened is a pain.

- Finger tighten all bolts first then work around tightening them up gradually, that is, do not fully tighten one side then move to the next, work around the pan tightening in portions, it took me 2 trips around the pan to have it all fully tightened. Again be careful as the pan is soft metal as is the trans so there is a risk of stripping if you are heavy handed.

- Clean up any drips/spills then proceed to the filling section again, but keep in mind that this time you will use closer to 4L so pay close attention to how much fluid came out.



- From the engine bay, remove the auto dipstick and place a funnel in the hole, I found that a screw on the battery clamp lined up perfectly with my funnel to hold it in place.

- Place some rags around the area just in case.

- To assist with pouring, I left the cap on and punched a hole in the lid with a large screw driver which gave me a nice controllable flow, I did this after spilling it first...

- Put back in what came out, in my case it was approx 3L (but could be up to 4L if you are pulling the pan/replacing the filter).

- Start the car and put it in drive then give it some revs and work through the gears and back again to get the trans temp back up.

- If you're confident you have the car level, you can check the fluid level while the car is up on stands, if not you will need to take it of stands first or make it level.

- The trans fluid must be at least 65 degrees and should sit on the full mark when at temp. A good drive or a decent run through the gears and at various speeds up on stands will do this for you, can feel the pan to get an idea of heat.

- Add fluid very slowly until the full mark is reached, it does not take a lot of fluid to go from low to full and if you overfill it you can have issues with how the trans functions.

- Clean up any spills and check for any leaks.

- Dispose of old fluid properly.





After draining it twice and replacing the filter (I replaced the filter AFTER the first drain to expose it to as clean a fluid as possible) the fluid on the dipstick is now a much nicer red and smells much better, it's also improved on what it was after only one drain.


Keep in mind that this method will use about 7L of your fluid, but will only replace 5-5.5L in the box as you lose some of the new fluid with the second drain. In my opinion though it's well worth it given how the fluid still looks after one drain.


The car didn't drive any different after this, which is a very good sign the oil was still working fine so hopefully we shouldn't have to think about it again for a while. I'd say I'll likely do a simply drain/refill in another 20ks. That's all an auto shop will do on a basic service also.


If you have any questions on this or any of the other things I've mentioned doing to this car, just PM me and if I don't reply (sometimes forums don't notify properly) just shoot me an email at daniel.fewster@gmail.com


I hope that's of use to someone.

Edited by ActionDan

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