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How to: Change your manual transmission fluid to synthetic (minor update 02/11)

160K views 267 replies 101 participants last post by  brandini 
#1 · (Edited)
Update log: Feb 24th 2011: Based on number of comments, I'm recommending 3 quarts instead of 4. Read the note about it below if unsure.

Hope this is useful. Let me know if you find any errors and I'll fix 'er up. My car is a 2006 Mazda3 Sport wagon. I'm assuming the 5-speed tranny is the same on all North American Mazda3's but correct me if I'm wrong...

I couldn't find a write-up for this so I thought I'd do it myself. I'm reasonably happy with the shifts on my 3, but I notice some notchiness there at times. I decided to try Redline MT-90. I'm in Southern Ontario, and managed to find Johnston Research and Performance in Mississauga as a retail seller of this oil. It's classified as a GL-4 and matches Mazda's requirement for a 75W90 oil. I'd read many good things about this oil in the past.


Usual disclaimer: These steps worked for me but double check your progress as you go. I can't be held responsible for any blah blah blah...

Things you'll need:

15/16" socket (mshu confirmed this is 23mm for the metric size) or wrench for the drain/fill plugs
Funnel and 3 feet of connecting tubing (recommended, you'll see I had some ghetto setup)
4 quarts Redline MT-90 UPDATE: 3 quarts Redline MT-90 or suitable synthetic 75W90 fluid (4 will cover you if you have any spills, the true capacity is 3.03 quarts) If you read the subsequent comments, most guys are more careful than me and needed only 3 quarts. Buy 4 if you're not sure if you can be spill-free.
Container that can hold at least 3 quarts
Usual tools for lifting the car and removing the plastic cover between the engine bay/underside of the front of the car (see any oil change write-up for these)

This was the first time I'd done anything to my Mazda3 (long time DIY mechanic on a old Nissan Maxima), so this was interesting for me.
I could see from the factory service manual and other reports that jacking up the car is easier if you drive it onto wooden blocks. I thought this was pretty incovenient, but I found out later that I could have done an oil change with the car just on the blocks.

Click any of the below images for a full size view - images are fairly large



I used the centre of the crossmember and put a piece of cardboard between my jack and the car body to prevent scratching.



I've had the dealer do the first couple of oil changes and could see from scuff marks from their lift, where I should put the jack stands.



After the vehicle was up on the stands, I removed the plastic shield that lies between the road and the engine bay (see any oil change guide on how to do this)

I realized I'd be best off with a level surface for the drain and fill, so I lowered the car back onto the planks. My garage is on a slight slope so it was probably level enough at this point.

Then I slid my waste pan under the drain hole (look at the top part of the image below, my screwdriver is pointing at it) and opened the bolt to start fluid flowing. The drain and fill holes are pretty easy to spot, they're the only bolts near the bottom of the tranny that are large (15/16", 23mm)



The fluid was a little slow to exit so I also opened up the fill hole (again shown by screwdriver) and then the fluid came out nice and quick.


Once the fluid had drained out, I replaced the drain plug. If you have an older car you may wish to replace the drain and fill plug gaskets. I've only had my car a few months and decided to skip this step.

Now for the interesting part. I would recommend buying a funnel with some 3 feet of tubing - it will make your life easy for the next part. In my case, it was almost a show-stopper until I found some regular copper piping normally used for residential plumbing. I had a funnel and 1 foot of flexible black tubing, but found it was not long enough. What you see in the next two images are the funnel, part of a turkey baster, copper tubing, and then on the underside of the car you can see the copper tubing going into flexible black tubing, finally going into the fill hole! Ghetto for sure, but it worked.




Take this step nice and slow, and put a clean container underneath. You'll need this near the end if you overfill, or in case you spill any (or if like me your crappy setup falls out). I found I used about 3.25 quarts, including a couple of spills. If you don't think you'll spill a drop, you may get away with 3, since the official capacity is 3.03 quarts in my owner's manual.

You know it's full when oil comes pouring back out of the tranny. Level with the fill hole counts as full - so if you've overfilled, allow fluid to come back out until it is reduced to the occasional drip, then replace the fill plug. At this point I gently moved the car through all the gears and waited ten minutes for things to settle. After that, it took a little more oil and then I called it a day.

I did not have a socket (I used an open-ended wrench) so was unable to torque down the drain and fill plugs accurately. I'll go back and do this later. The torque specs call for 29-43 ft-lbs in the factory service manual.

The shifting is noticeably easier, especially in the 1-2 shift which I used to find was quite notchy. To me, this was a worthwhile spend of about 60 dollars Canadian (inc. taxes), and would take the average person about an hour or two.
 
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#2 ·
Re: How to: Change your manual transmission fluid to synthetic

very nice

props

how is the felling of the tranny after the oil change? i mean after about couple of hundred km
 
#4 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=davey6693 link=topic=66350.msg1138198#msg1138198 date=1168230252]
Hope this is useful. Let me know if you find any errors and I'll fix 'er up. My car is a 2006 Mazda3 Sport wagon. I'm assuming the 5-speed tranny is the same on all North American Mazda3's but correct me if I'm wrong...

I couldn't find a write-up for this so I thought I'd do it myself. I'm reasonably happy with the shifts on my 3, but I notice some notchiness there at times. I decided to try Redline MT-90. I'm in Southern Ontario, and managed to find Johnston Research and Performance in Mississauga. This oil is classified as a GL-4 and matches Mazda's requirement for a 75W90 oil. I'd read many good things about this oil in the past.

[/quote]

Thanks davey! 1 question: where is the fill hole located? I didn't see where you referenced it.
 
#7 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=NoVa link=topic=66350.msg1139855#msg1139855 date=1168313698]
Ha ha. Thanks DB!
[/quote]

No problem! :D

You know, this has to be the first car that I know of, that the auto is actually easier than the manual to drain and refill the fluid. :p



Darryl
 
#8 ·
Re: How to: Change your manual transmission fluid to synthetic

can you please post the pictures but with a better resolution, or thats the max resolution (cellphone?)
 
#9 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=hate_romania link=topic=66350.msg1139899#msg1139899 date=1168314690]
can you please post the pictures but with a better resolution, or thats the max resolution (cellphone?)
[/quote]

Done - click images for high-res view
 
#10 ·
#11 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=mshu7 link=topic=66350.msg1140413#msg1140413 date=1168354739]
Nice write-up!

For anybody that's interested, there's more information in this thread I created a while back: http://www.mazda3forums.com/index.php?topic=33727.0
[/quote]

Thanks Shu. I had that bookmark also.
 
#14 ·
Re: How to: Change your manual transmission fluid to synthetic

Nice write up!!!
Next open day I'm switching my fluid out.
Forgive me for my slowness
But I noticed this is a 2.3 model...
Any differences in 2.3 vs 2.0?
And where can I Purchase the drain and fill plug gaskets
 
#15 ·
Re: How to: Change your manual transmission fluid to synthetic

The trans. on the 2.0 should be the same. I wouldn't worry about the plug gaskets. I didn't replace mine and I've had no issues. If you want to get them still, I'm sure the dealer would have them for sale.
 
#16 ·
Re: How to: Change your manual transmission fluid to synthetic

Also...I'm very careful with over fill when I do My oil changes.
It sounds to me that it would be almost impossable to overfill the trans fluid..just the simple fact that it would drain out of the drain whole.
So I guess what am asking is...well...I don't want to under-fill or over fill Any way of measuring? Or just dump 3 qts in and call it a day?
And Redline MT-90...Any issues with factory warrnty? I wouldn't think so......
Sounds like good stuff
Nice write up by the way!
 
#17 ·
Re: How to: Change your manual transmission fluid to synthetic

Look at it this way:

Your trans takes 3.03 qts. of fluid. When you drain the fluid, you're not getting 100% of the fluid out (fluid that remains on walls of casing), but close. There's your .03 qts. When you put in 3 qts. you're right back where you need to be.

So, put in 3 qts. and call it a day.
 
#18 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=mshu7 link=topic=66350.msg1141403#msg1141403 date=1168385599]
The trans. on the 2.0 should be the same. I wouldn't worry about the plug gaskets. I didn't replace mine and I've had no issues. If you want to get them still, I'm sure the dealer would have them for sale.
[/quote]

Yep it is the same. I did the change to redline mt-90 last summer in my 2.0 MZ3. +1 on the plug gaskets. I reused mine and no leaks.
 
#20 ·
Re: How to: Change your manual transmission fluid to synthetic

My old fluid looked fine but i had only about 13,000 miles or so when I changed it. However I must say that shifting improved quite a bit with the redline so whatever they use from the factory does a pretty poor job with the synchros imo.
 
#21 ·
Re: How to: Change your manual transmission fluid to synthetic

The Redline products along with Amsoil are quite possibly the best fluids out there anf the use of them does nothing to void warrantees.

Most of the time, the service monkeys wont know about them if the repairs have nothing to do with the trans or brakes.
 
#22 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=Spaz218 link=topic=66350.msg1141418#msg1141418 date=1168386125]
Also...I'm very careful with over fill when I do My oil changes.
It sounds to me that it would be almost impossable to overfill the trans fluid..just the simple fact that it would drain out of the drain whole.[/quote]

Yeah - it's pretty hard to go wrong here. To be absolutely certain you're full, just overfill a little and allow the excess to drain out.
 
#23 ·
Re: How to: Change your manual transmission fluid to synthetic

Does the tranny still feel nice after you get some miles on it?

Basically, does it stay nice or does it go back to notchy after a 1000 mi ?
 
#24 ·
Re: How to: Change your manual transmission fluid to synthetic

Man Redline is hard to find...
Called auto Zone..no
Advanced auto parts...no
A performance shop called Bigfoot...no
and still no redline...lol
I think I might order it from summit but it has to get here by..friday..lol
 
#26 ·
Re: How to: Change your manual transmission fluid to synthetic

[quote author=speedfreak89 link=topic=66350.msg1142356#msg1142356 date=1168439057]
Does the tranny still feel nice after you get some miles on it?

Basically, does it stay nice or does it go back to notchy after a 1000 mi ?
[/quote]

Stays nice.
 
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