As heading says I am planing on changing my gearbox and diff oil next week I’ve seen the download section but if anybody has done this job what grade of oil and litres needed and any other tips which will help me out do I need 2 litres of oil for the gearbox and 1 litre of oil for the diff and is the gearbox and diff oil the same  and is the grade SAE GL 4 or GL5 /75 /90 and spanner sizes for a Mk3 are they 23m and 24m  for the diff and 14m and 17 m for gearbox ? Also what size washers do I need to get from local shop ready thanks allÂ
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The MK3 can use any GL5 75w/90 in the back axle. Use any crush washer between 18.5mm and 20mm inside diameter so two for the back axle. You need an 23mm and a 24 mm spanner or socket. Tighten all the bolts to 30 lbft if you have a torque wrench on the back axle and gearboxes.
The gearbox is different and a bit more complicated and harder to fill.
If you have a 5 speed box then the fill plug needs a 14mm open ended spanner and has no crush washer.
Use if possible a GL4 70w/90 gear oil if you can use Redline MT90 or Castrol Syntrans Multivehicle 75W-90.
If using Castrol it is important to get this specific oil.
The later two are very good for notchy gearboxes.
The drain plugs is 24mm and you need a similar size crush washer to the above.
It needs 2 litres of oil.
The 6 speed box needs either of the two mentioned oils not a general gearbox oil. It needs 2.1 litres so you need to get 3 litres.
The fill and drain plug are both 24mm and each need a crush washer between 18.5mm and 20mm inside diameter.
Yo need some sort of syringe to fill the gearboxes and if you do not have access to a pit or ramp it’s a good idea to possibly get a garage to do the gearbox but give then the two oils mentioned because they will just use a general oil which is not good on a 6 speed box.
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Thanks Eddie that’s great
Hi,Just a few questions.
1) Are the instructions re oil change for 6Â speed Gearbox and Diff relevant to the Mk3.5 as well as the Mk3?
2) Is there a problem identifying the drain plug on the 6 speed Gearbox ? I believe I remember a caution in the dim and distant past that there is an identical plug near the drain plug which can drop a lay shaft in the gearbox if it’s removed by mistake?
3) I understand there is oil required in something called the Turret?? which may also needs changing?
I’m asking because I need to do mine before June of this year and I’m pretty clueless about it.
Cheers
Gales
Hi Gales,
Yes they are. It is exactly the same procedure for the 6 speed gearbox on the Mk3/3.5/3.75. It is the same gearbox, bar some internal tweaks.
Not really. Both plugs are on the left side of the gearbox. The drain plug is really low and there is nothing around it. There is an adjustment on the left side but that is quite high close to the turret and you really need look for it, so don't worry about that. Anyway, here is a picture with the left side of the gearbox with the plugs highlighted (view from the rear of the car):
(image taken from this thread: http://forum.miata.net/vb/showthread.php?t=424846 )
You can also change the turret oil. The turret takes around 200ml of oil. I don't think it is a requirement but it is good to do it. Not only for the oil, but to clean and grease the lever ball which gets dirty with a lot of debris from the rubber boot under the lever gaiter. But that is a completely different job, you don't have to lift the car. just need to remove the center console trim. Check this thread (post #24 has a pictorial of the turret):
Cheers,
Adrian
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Very handy guide above for the on the Mk3, I plan on doing mine this year.
Quote…
“2) Is there a problem identifying the drain plug on the 6 speed Gearbox ? I believe I remember a caution in the dim and distant past that there is an identical plug near the drain plug which can drop a lay shaft in the gearbox if it’s removed by mistake?”
There was a guide somewhere on this forum about this above, it related to the 6 speed box on the Mk2 and may be the Mk2.5 as I had to be careful which plugs I used to change my oil on my previous RS 6 speed.
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The washers are 9956-41-800 24mm OD x 18.25mm ID x 1.4mm thick, solid copper or ally, either will do (the diff drain was copper on mine iirc). They are all the same Mk1, 2 and 3 for gearbox and diff but the 5 speed boxes don’t need one on the filler as it’s taper plug. I got mine here
Oil as Eddie says, I used the Castrol Syntrans 75W90 GL4 in the gearbox with good results, and a different GL5 in the axle.
Having done it twice I wouldn’t start the job without an oil syringe/gun from Machine Mart or similar. Although that picture makes access look good, in practice it’s pretty tight even on a lift. It’s great for doing the turret oil too (console and gearlever out, separate job as Adrian says, and probably not needed unless you’ve done a lot of miles, ours was fine at 30K). I did read about someone complaining the gun leaked so do put your finger over the plastic tube when offering it up to the filler hole! http://www.machinemart.co.uk/shop/product/details/cgg500-500cc-oil-suction-gun
Yes the plugs are 23mm and 24mm but if you don’t have them but have a selection of older sockets check the 15/16 AF (23.8mm) and 1/2 Whit (23.3mm) as they also usually fit.
Â
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Many thanks to you ALL for the informative advice. The picture was particularly useful, thanks Mac.
“A picture is worth a thousand words”Â
Best Regards
Gales
Well it’s dry outside I had an early start on the oil change on the 5 speed gearbox on a mk3 2006 plate I found my fill plug I could loosen with my hands ?? So good job I was doing this job the fill plug was a size 14mm and the drain plug was a 24mm so all good I drained the dirty smelling browny black oil while it drained out I cleaned the plugs up and Cooper slip and new crush washers then I replaced the drain plug and used my large sirringe from screw fix excellent bit of kit for this job the gearbox took 2 litres of castrol syntrans multivehicle 75W/90 GL4 oil and after I finished I noticed a difference straight away placing the gear shifter in reverse to come off the ramps it didn’t feel tough it went in smooth I then tried out all the gears and they are all smoother
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I’s use GL5 for the diff though.
It is also much easier if you stand the oil bottles in a bucket of hot water for 10 minutes first.
If the MK3 6 speed boxes are like the MK2’s you can fill them through the turret.
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That would be a help if it is the same as the Mk2 6 speed as that was the way I did mine on the Mk2. It was easier that way as I had to do the shift upper and lower boots at the same time.
Anyone know if it is the same on the Mk3 6 speed?
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No you can’t I’m afraid Mick, Mk3 6 speed is a completely different box with separate turret oil.
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Yes that’s right Nick I used 1 litre of GL5 in the Diff 23mm and 24mm sockets and the Diff oil stunk very bad
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USING TOTAL DUAL 9FE 75W-90 OIL.
This clarifies the point of GL4 and GL5 MK 3 Gearbox oil (and may apply to other models too).
Therefore, no need to worry about using this Total oil.
MY EMAIL TO TOTAL UK.
Hi l have a Mazda MX5 2.0 2013.
I have just changed the 6 speed transmission oil based on your
recommendation. i.e Dual 9 FE 75W90. I have been told I should
only use a GL4 oil due to the additional chemicals used for a GL5
oil which can harm the synchromesh hubs etc. But as you list
suitable for both GL4/5 I am now very confused! Is it safe to
use? Many thanks.
REPLY FROM TOTAL.
Technologies have changed but the performance levels have stayed the same. In some of the GL5 oils they contain twice as much EP Sulphur Phosphorus additives as a GL4 and this can affect copper in synchromesh.
Using the new technology in Transmission Dual 9 FE 75W/90, different chemistry has been used to get both performance levels without affecting the synchromesh yellow metals.
I hope this explains everything.
Best regards,
BobÂ
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|
Bob Wood
Technical Engineer TOTAL UK LIMITED Lubricants Division |
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Just changed the transmission oil on my 2007 1.8 Mk3
And like you my fill plug was loose and could be removed by hand. When you screwed it back in were you able to torque it up to the specified amount?
Cheers
Miles
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