Any MTF that Improves Notchy Shifting?

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Seems like I read on here where a couple of y'all said you upgraded to Redline MTF and it improved shifting.

I have a 2016 WRX, just hit 30,000 miles, so I figure it's time to service the gearbox and differential(s).

The shift action is OK; not what I'd call slick. If I could improve it by even a few percentage points, I figure why not?

Suggestions? Anybody used any other MTF that seemed to noticeably improve shifting?

Another thing while I've got y'all here - the diff seems to be binding (in cold temps only) when I pull out of the driveway (steering wheel turned to 75% of full-lock). It does not happen once the fluid is warmed up.
 
Originally Posted By: d00df00d
Originally Posted By: skyactiv
This is a true 75W90 PAO synthetic fluid made in Germany. It is cheaper at a Ford dealer.
The fluid is very popular with Miata owners. Look at the reviews on Amazon.

https://www.amazon.com/Genuine-Ford-XT-M5-QS-Synthetic-Transmission/dp/B000NUES82

Using this myself. The 2009+ RX-8 shares a transmission with the NC Miata. Liking the fluid so far.


This. I had an NC Miata until 2 years ago. I changed to Redline fluid and it did help. Learned of the Ford fluid and changed to it. Significant difference for the better. It takes maybe 100 miles or so to become fully effective.

If your car specs that kind of fluid, I highly recommend it.

There will be others who warn of imminent transmission destruction if not using "factory fluid". If the Ford fluid is not the specs your trans needs, I'd agree (maybe). But if it is, use it.
 
Originally Posted By: Mr Nice
What about Amsoil MTF ?


+1. In my 91 BMW, I ran redline for a long while and it would get notchy after a short time. Moving to Amsoil gave a much more consistent feel and performance.
 
Motul Gear300. Mix in a bit of Redline Shockproof if the Motul alone does not get the job done.

Have you done a search at nasioc.com for gear oil recommendations?
 
Last edited:
Originally Posted By: john_pifer
Seems like I read on here where a couple of y'all said you upgraded to Redline MTF and it improved shifting.

I have a 2016 WRX, just hit 30,000 miles, so I figure it's time to service the gearbox and differential(s).


How has the factory fluid served you during the first 30k miles?

When I changed the manual transmission fluid in my 2014 Mazda 3 with the OE Mazda juice, shift quality improved significantly. No need to change brands or try some super fluid from Germany.

In my opinion, the only thing that your WRX needs is a simple fluid change to flush out suspended wear particles that may be getting in the way of the syncronizers meshing together smoothly. The fluid could also be deteriorating a bit (it's not performing @ 100% like it was when it was new) and fresh juice with new additives will definitely perform better then your current 30k old oil. Trust me.

By the way, what's the WRX community recommend? Have you seen any reviews of other members and their experiences?
 
GM Synchromesh is the way to go; if it's too thin for your application, you can thicken it up with a 75w-90. In fact, the Subaru community has been doing this for decades. They call it "Uncle Scotty's Cocktail"

https://forums.nasioc.com/forums/showthread.php?t=920674

I personally wouldn't put the Redline shockproof in there. I'd do 1 quart of GM friction modified synchromesh and the rest Ford 75w-90 GL-4 conventional MTF. They discontinued it but most Ford dealers still have it in stock. That cocktail made my Corolla go from feeling like it needed a new transaxle to shifting like buttah.
 
Here is a list of 75W90's.

Note: The WRX transmission shares a sump with the differential so the MTF hass to be GL-5 rated:

G. The next higher viscosity MTLs in the 14-15 cSt (SAE 75W90) range would be:

1. Amsoil MTG
2. Redline MT-90
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT (Carries a GL-5 rating as well)
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QS
7. Subaru Extra-S Gear & Transmission Fluid carries a GL-5 Rating because it is used in common sump driveline systems. [May have been discontinued]
8. ACDelco 10-4059 GL-4 75W-90 Manual Transmission Fluid
9. ACDelco 89021806 For use in MA5 manual transmission for GMT 345, GMT 355 Trucks and GMX 020 Cobalt Pursuit and G5 Passenger only. Caution: Rated at GL-3 (ExxonMobil fluid).
10. RAVENOL TSG SAE 75W-90
11. LiquiMoly 75W-90 GL4
 
Last edited:
Originally Posted By: john_pifer
Seems like I read on here where a couple of y'all said you upgraded to Redline MTF and it improved shifting.

I have a 2016 WRX, just hit 30,000 miles, so I figure it's time to service the gearbox and differential(s).

The shift action is OK; not what I'd call slick. If I could improve it by even a few percentage points, I figure why not?

Suggestions? Anybody used any other MTF that seemed to noticeably improve shifting?

Another thing while I've got y'all here - the diff seems to be binding (in cold temps only) when I pull out of the driveway (steering wheel turned to 75% of full-lock). It does not happen once the fluid is warmed up.
I've been pleased w/ Redline in Mazda MTs (2001 Protege and 2009 Mazda 5), but they both required a GL4 fluid. (GL5 cntains sulfur, which is detrimental to the yellow metal synchronizers.)

Because your Subie requires a GL5 fluid, look for one that's 'grabby' enough to get the synchronizers operating properly.
 
Originally Posted By: eagle23
Originally Posted By: skyactiv
This is a true 75W90 PAO synthetic fluid made in Germany. It is cheaper at a Ford dealer.
The fluid is very popular with Miata owners. Look at the reviews on Amazon.

https://www.amazon.com/Genuine-Ford-XT-M5-QS-Synthetic-Transmission/dp/B000NUES82


It was a couple years ago, but at the local dealer it was more like $20-21/quart. Call around to local Ford dealers.


The last time I checked (about 2 years ago) it was in the $22.00 to $23.00 a quart range here in eastern Pa. dealers, and at the local small chain (3 or 4 stores) parts store which stocks Ford/Motorcraft fluids.
 
Originally Posted By: SubLGT
Originally Posted By: skyactiv
This is a true 75W90 PAO synthetic fluid made in Germany. It is cheaper at a Ford dealer.
The fluid is very popular with Miata owners. Look at the reviews on Amazon.

https://www.amazon.com/Genuine-Ford-XT-M5-QS-Synthetic-Transmission/dp/B000NUES82


The WRX requires a GL5 rated fluid in the transmission. Is this fluid GL5?

Oh dang. Missed that this thread was about a WRX.

XT-M5-QS definitely is not GL-5.

Isn't Motul Gear 300 a popular choice for Subie gearboxes that call for GL5?
 
Yes don't even think about putting a fluid in there that is not rated for hypoid diff gears. I have a similar Subaru as well and it seems to be a be tricky to find a fluid that offers GL-5 protection and great shift feel / syncro operation.

The Motul gear 300 is what I am using. I've heard you can mix in some RL lightweight shockproof for better feel (up to 25%) but you are most likely sacrificing some protection.
 
Originally Posted By: slacktide_bitog
Redline seems to recommend 75w90 NS GL5 (part number 58304)


This looks like a good one but no one on the Subaru forums seems to talk about it. Everyone all about the Motul Gear 300!

Also RL Shockproof is some interesting and different stuff... suspended "solid microscopic particles"?
 
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