Worn synchros - fluid change good or bad?

[Short_Bus]

The transmission in question is a Ford MTX75 in an 05 Focus.

As is typical with this trans, the 3rd gear synchro is shot. You have to shift really slowly into third or it grinds badly. It has progressively worsened over the last couple of years. I'm sure it still has the original fluid which is now 150k miles and 11 years old.

Normally I would have no second thought about changing the fluid. It seems it would never be a bad idea. The reason for hesitation is what effect would the potentially increased lubricity of the new fluid have on the synchros? Would the increased "slipperiness" of fresh fluid help or hurt their performance? I really don't have any idea how synchros work but I wonder if they need some "traction" to operate.
And for what it's worth, I was planning to try the Motorcraft manual transmission fluid (honey) that is spec's for the MTX and costs ~$25/qrt.

 

[double vanos]

You're talking about motorcraft XT-M5-QS. Pretty good stuff. My first Mazdaspeed 3 had a horrible 1-2 shift grind and that stuff fixed it completely. If you can afford it, I'd give it a try.

 

[Brybo86]

Worsened over the last few YEARS? What are you waiting for? Change it!

 

[RooflessVW]

Change the fluid!

 

[Leo99]

I'm in the don't change ATF camp but if the transmission is on its last legs, changing it might help. What do you have to lose?

 

[barkingspider]

I would change the fluid like yesterday

 

[RooflessVW]

Originally Posted By: Leo99
I'm in the don't change ATF camp but if the transmission is on its last legs, changing it might help. What do you have to lose?


The key word in his post is "synchro."

His transmission is a manual.

 

[jhellwig]

Stop using the clutch in that gear if you wanna keep getting by.

 

[Michael_P]

When I hear of a MT syncro going bad in small cars, oftentimes symptoms worsen after a few thousand miles after a fluid change. If you are not the original owner of this car, I wonder if someone put in a GL-5 fluid in there. If you are uncertain, change it pronto as others have said. Put the XT-M5-QS in there which according to Ford is the only fluid that should go in there. I takes barely over two quarts, so even at $25/qt, it might be a sacrifice, but it shouldn't break the piggy too badly. At least not compared to putting the wrong fluid in there. The XT-M5-QS is definitely worth it.
If a GL-5 fluid is in there, you will smell it when you drain it.

 

[demarpaint]

All changing the fluid is going to do is get junk and worn syncro material out of the transmission, and get fresh clean fluid in there. Other than that it isn't going to help. If you don't plan on fixing it try double clutching going into third gear.

 

[yvon_la]

What does ford ask? Gl-4 oil? Get a allison tes-295 (with an official allison number for tes-295)is it a gl-5. Then get an sae j2360 oil

 

[mazdamonky]

GL5 fluid is supposed to be acceptable in most of those cars according to their service manual. However, in my rx7 I switched to redline over what was originally in it when I bought it. It had slight notchiness that was seeming to get worse. When I looked at the service record, it did have some gl5 fluid put in it recently. I switched it to the redline and it got considerably better. Slightly more notch than the original notch, but not near as drastic as before the switch. My next fluid change will probably be one quart of the redline I have left and 1 quart of the ford stuff. Or I may just do two quarts of the ford stuff. Either way switching to a proper GL4 synthetic made a difference.

 

[zeng]

Originally Posted By: Michael_P
When I hear of a MT syncro going bad in small cars, oftentimes symptoms worsen after a few thousand miles after a fluid change. If you are not the original owner of this car, I wonder if someone put in a GL-5 fluid in there. If you are uncertain, change it pronto as others have said. Put the XT-M5-QS in there which according to Ford is the only fluid that should go in there. I takes barely over two quarts, so even at $25/qt, it might be a sacrifice, but it shouldn't break the piggy too badly. At least not compared to putting the wrong fluid in there. The XT-M5-QS is definitely worth it.
If a GL-5 fluid is in there, you will smell it when you drain it.


What makes you think that GL5 IS being used in this MTX75?
Cos' this synchro defects IS caused by GL5 ? ...... omg

 

[Olas]

The potential band-aids for this situation are to try the correct fluid, and to rev match more accurately.
Neither are as good as replacing the syncro.

 

[HerrStig]

Originally Posted By: jhellwig
Stop using the clutch in that gear if you wanna keep getting by.
Just exactly how does THAT work?

 

[JamesBond]

I'd drain and fill with Pennzoil synchromesh mtf for $9 a quart to see if it helps before I spend the money on the ford stuff. Worse case scenario is it still shifts bad but at least the box gets flushed out a bit before you try the ford stuff.

I've used synchromesh in all kinds of manual transmissions, and it seems to work well in everything. It's thinner than the ford stuff mentioned above but whatever.

 

[Olas]

Originally Posted By: HerrStig
Originally Posted By: jhellwig
Stop using the clutch in that gear if you wanna keep getting by.
Just exactly how does THAT work?


Accurate rev matching and a delicate touch. Yu only need to use the clutch t move away in 1st and hen you can use talent and finesse to go up and down the gears without the clutch AND without any grinding.

 

[4wheeldog]

I would try Redline MT90, or MTL, whichever is the appropriate weight. It makes synchros work better than anything else I have tried.

 

[IndyIan]

I just use the Ford stuff XT-M5-QS, but the annoying part is that you need 3 bottles... My Focus somehow got ATF fluid in it by the PO going to iffy lubes, but seems to have survived.
Read through some Focus sites, as all this has been gone over a few times there.
I do like the idea of the cheaper pennzoil flush first though, as it might work and if not, you have a cleaner gear box to try the Ford fluid.

 

[Olas]

Originally Posted By: 4wheeldog
I would try Redline MT90, or MTL, whichever is the appropriate weight. It makes synchros work better than anything else I have tried.


+1! Amazing improvements in shift characteristics with MTL, MT85 and MT90.