Ford Synthetic Manual Trans Fluid

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NO. But I am intrigued - it looks real good on paper.
It IS expensive, so I haven't dived in yet just to test it.
I am having success with Redline presently, and am in no hurry.
But the new Ford fluid appears to be very good.
 
SO what viscosity is speced for your son's RX-8?

From the MSDS' 40C viscosity, it appears this mtl MIGHT be a 75W85?
 
Originally Posted By: MolaKule
SO what viscosity is speced for your son's RX-8?

From the MSDS' 40C viscosity, it appears this mtl MIGHT be a 75W85?


75W-90 for the Mazda.

Most on the RX-8 boards use Amsoil or Redline successfully.

The RX-8 guys also use the Royal Purple stuff and are real happy with it until the synchronizers go out. :)
 
That fluid, XT-M5-QS, is not GL4. It says it is suitable where GL4 is specified. It is made by Castrol and is not available in the US under the Castrol label.

Ford specifies it for use in the Contour / Mystique / Cougar / Focus MTX75 5 speed manual transaxle. It is very nearly a 10W40 synthetic motor oil but with a very high TBN. Last I knew, Royal Purple cataloged their 10W40 synthetic motor oil as their recommended replacement although many Contour owners use Royal Purple's manual transmission oil instead. XT-M5-QS works especially well in the MTX75 transaxle, but I would be reluctant to use it in other transmissions. It's additive package falls way short of that of other gear oils.
 
I appreciate the insights, Big Jim.

It says GL-4 and 75W-90 and I thought I was good to go.

Mazda and Ford seem to be getting closer with a lot of vehicle relabeling going on.

The stuff is good enough for a lifetime fill in the Ford, I thought the Mazda would like it too.
 
Big Jim - Are you sure you are talking about the newest Ford Synthetic fluid? It is designed for manual transmissions exclusively.
 
Originally Posted By: mechtech2
Big Jim - Are you sure you are talking about the newest Ford Synthetic fluid? It is designed for manual transmissions exclusively.


I'm talking specifically about the Morotcraft fluid with the part number mentioned by the OP. I should mention that I have this fluid currently in my Contour SVT and it works extremely well. I'm just reluctant to use it in other transmissions, especially one that may need better EP protection.

Last time I looked over the Motorcraft catalog there was another fluid released later for the Ford GT that may be more of a gear oil.
 
The Motorcraft XT-75W90-QGT for the Ford GT is a GL-5.

Other Mazda owners are having problems with GL-5 EP type fluids in their transmissions.

These problems seem to be more than anecdotal.

I just got the Motorcraft XT-M5-QS in from a internet supplier.

I'll probably take the leap and install it this spring.

I have a few miles before the change is actually due.
 
GL5 should not be a problem if it is specifically blended for manual transmission use. There are various additives available to bring it into GL5 specs, and selecting the correct ones in the right balance with the correct base stocks can end up with a superior manual transmission oil.

Stay away from gear oil that is intended for differential use.
 
in the miata forums, this is the stuff to beat, and nobody has done it yet (besides Molakule's former SF elixir). i believe the NC miata's have the same transmission as the RX8s. i do know that anyone that uses a GL5 in a miata 6spd is asking for rough shifting, and that this stuff will calm it down quite nicely. note that after using a GL5, it may take up to 3k miles for this stuff to get to full effect as the coatings wear off the synchros.
 
Originally Posted By: cheetahdriver
in the miata forums, this is the stuff to beat, and nobody has done it yet (besides Molakule's former SF elixir). i believe the NC miata's have the same transmission as the RX8s. i do know that anyone that uses a GL5 in a miata 6spd is asking for rough shifting, and that this stuff will calm it down quite nicely. note that after using a GL5, it may take up to 3k miles for this stuff to get to full effect as the coatings wear off the synchros.


Thanks for the reassurance, cheetahdriver.

The gearboxes on the Miata and RX-8 are reportedly very similar. That's why I thought the application would be a good one.

My son's RX-8 is working fine right now.

But I have noticed a slight slowness of the synchros in the lower gears.

It's probably still the factory fill in the car with 50,000 miles on the clock.
 
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