is it fit USDM same with JDM on using transmision oil ?
Honda recommended for JDM Jazz is 10-40w or 10-30w. is it same in USDM Fit ?

thanks

 

I'm about to change the GD3's trans fluid for the first time but am kinda tempted to use a full-synthetic MTF...

Honda Engineers are world-class, but for something you only change every 30k miles I think $20 more might be worth smoother shifts & possibly longer tranny life.
But I would give Honda the benefit of the doubt that simply changing your conventional Honda MTF (II) on schedule should help transmission last hundreds of thousands of miles

The most tempting I've found is Motorcraft's full synth MTF, I use it in my Miata & its niiiiice, but expensive...

 

ALWAYS, ALWAYS use the transmission fluid required by manufacturer. Its not like engine oil.
And about that 30k change interval ...
Most manufacturers transmission and gearing engineers work closely with oil suppliers to get a formulatiuon that yields the best operating and wear results.Many times the 'standard'formulations work just fine but not always. Friction modifiers and viscosity improvers concentrations or chemicals are not always best for every transmission.

An example might be what happened to Honda in IMSA racres wherebrake fluids were 'imporoved' by teams choosing hiher performance spec fluids and discovered the proportioning valve had seals that weren't compatible and failed so rear brakes gut full pressure. Guaranteed rear brakes wore out rapidly.
Unless a supplier recommends their fluid specifically I'd stick with Fit recommended fluids.
The odds of an aftermarket use is a small risk but nevertheless is can be a risk.

 

You know about API specs right? Honda's MTF-II (stock Fit fluid) is a 75w85 GL4 fluid from natural base stocks (conventional) with friction modifiers and a wide temperature range. This means its modern, durable, flexible & cheap (All things Honda likes!)

The Motorcraft synthetic MTF is a 75w90 GL4 full synthetic with friction modifiers with a wide temperature range as well, just more swung to higher temperatures. This does mean it may be less smooth on colder days & the first few miles. Ford/Mazda calls it a "lifetime fill" fluid, supposedly only replacing it if the trans case has to be opened for service.

But when your banging shifts like a madman, its more resilient to shearing, & friction/thermal breakdown. Downsides? Usually found for $15 or more per quart & the less smooth while cold part.

Oh & 30k is Honda's recommendation but yeah I'd change mine sooner too.

 

I changed mine for the first time at 50k miles. haha it does wonders.... sadly someone grinded my gears two hours after we put in the fresh mtf.. i just went with honda mtf to save myself the headache of figuring out if its safe for our trannys..

 

Yeah really.
The only thing I can find in Honda literature for the MT is to change it when the Maintenance Minder displays a #3.

I found one reference from a guy who changed his at 84k, sounds like he went by the minder's recommendations:
Hello, Honda, can't you give us some ballpark idea of the mileage interval for MT fluid change?

 

I change mine every spring time before the lapping season starts(about everything 20,000km-ish). I've been using the Motul Motylgear 10w40 GL4 fluid for a long time. Works great for me even at -10c or so. And driven Kspec's KWSC fit with Mfactory helical LSD & my bro put in the Torco transmission fluid, shifts smoothly as well.

Check out what these guys say...

MFactory Competition Products - Forged Transmission Components

 

The key is which friction modifiers, viscosity controllers, and surface tension controller compounds are best. Only the manufacturer knows for sure. But as you say, a good quality aftermarket fluid is likely only a small risk. Just how much is a small risk? For all we know Honda may use the same stuff as Motorcraft branded fluid. Both Ford and Honda buy their fluids from suppliers that they work closely with in the lab.

 

^^ Good point!

Well I gave the Motorcraft synthetic MTF a go last night. Shifts smooth & it was below 32*F on my 30 mile test drive. Anythings better than tired assembly plant fluid after 0-30K miles, but I'd say I like the "feel" more of the very slightly thicker Motorcraft juice.

Yes, its not Honda's OEM fluid so it could have some unforeseen adverse effects in the long run, but I hope to be a Honda pioneer of MCSMTF. It's performed very well with my Miata family so far.
(Random useless fact: Mazda used the same Aisin 6-speed as the S2000 in NC1 & NC2 Miatas)

Motorcraft Full Synthetic Manual Transmission Fluid - MX-5 Miata Forum

 

Cite please. Everything I've read (including the car's owner's manual) suggests that Fits use something more like 10W40 in the manual transmission. Something as heavy as 75W90 has the potential to do real damage to transmission components that are expecting much, much thinner oil.

A reference to demonstrate my point: Amsoil recommends their MTF for Hondas; it's 5W30.

AMSOIL - Transmission Products and Fluids

AMSOIL - Synthetic Manual Synchromesh Transmission Fluid (MTF)
Cite request for this too, please thanks. I believe that the change interval is much, much longer for all but the most severe conditions.

 

Great read with this thread! My 2008 Fit is sitting at 44k right now and I plan on changing my MTF with the good old Honda MTF right at 50k 'ish.

I've used Honda MTF in my S2000, Civic, Accord, and my wife's RSX with great results. So to me there is no reason to change unless someone has some proof that another oil is better at about the same cost.

 

Look at the chart here Viscosity Charts

as you can see, gear and engine oils fall within similar viscosity ranges despite their numeric designations.

 

Can you post some links that show this?

 

As I see (as a Chemical Engineer who worked for a petroleum company during my career) there are considerable differences in viscosities of SAE 10, 20, or 70 or 80. Putting a gear oil in an engine would be very bad for the engine when the engine has to work hard. Might not make much difference at idle but at work yes.
THEY ARE NOT SIMILAR in viscosity and worse, may have entirely different additives that make their use recommended. Those charts do not really show the differences in work required to determine the internal fluid resistances.

 

Here is a link for Mobil 1 75w90 Mobil 1 Synthetic Gear Lubricant LS 75W-90

it has viscosity @ 40C 106 cSt and 100C 15.2 cSt

look here at Mobil 1 10w40HM Mobil 1 High Mileage Oils

it has viscosity @ 40C 98.16 cSt and 100C 14.71 cSt

I guess I should have said they have similar kinematic viscosity...
However, I agree that you should never put gear oil in an engine, but I thought this thread was about oils for the Fit manual transmission.
In the 2008 Honda Fit manual it states that you can use 10w40 motor oil if Honda MTF is not available as a temporary replacement. Someone said that 10w40 and 75w85 were similar, just wanted to note they are close in kinematic viscosity.

Just for the record I think that you should use Honda MTF in the manual transmission. What is the point in messing around with other brands? If you are concerned that the oil will not make it 30k miles then change it sooner. Everyone should listen to mahout, there is a lot more to oil than just viscosity, additives and the like are used and targeted to their specific application, i.e. the transmission's requirements.

 

I've used Motorcraft MTL in my Mazda and LOVE LOVE LOVE it. Seriously debating on trying it out in my '09 Fit. Seems you are the first! Any reports on how it's been holding up?

I need a change soon (spring) and my top candidates are Amsoil or Motorcraft, followed by OE fluid.

 

We use Amsoil in both our Fits.

 

Amsoil all the way

 

I changed mine at 70k kilometres (50k miles) because I didn't know if the previous owner had ever changed it. I was having trouble shifting into 1st. It did improve things slightly but I still find myself occasionally struggling to get my GD fit into 1st. I end up returning the stick to neutral and trying again. Used 1 and 4/10ths bottles of Honda MTF for the flush and change.