2013 Scion FR-S | Transmission Fluid Questions

[nicknak]

Hi, first time poster, long time lurker. I've tried to research as much as I could before posting, so help me learn!

[Preface]

Recently purchased a 2013 Scion FR-S for double duty use as a daily and a frequent autocrosser. Factory fill for the transmission, I believe, calls for a 75w90 GL3.

Trying to research which fluids would be best to use in this car. I'm finding many people have frustrations with the transmission when the fluid cold, and that gears are harder to go into, and sort of grind if you force it. I'm finding this to be true, but as the fluid heats up, it goes away.

The fluids that are recommend to me by a popular local tuner (and by others on FT86club) are Motul 300 and Pentosin MTF2.

[Questions]

The pentosin is frequently recommended for colder temperature locations (I'm in the PNW, so not terrible) and I have read it eliminates those issues... However, after emailing CRP Automotive, the MTF has been discontinued as of 2 years ago.

I found the Dedicated MTF Fluids list, and see that it's sorted by Kinematic Viscosity.

1. Are there any other factors to consider besides Kinematic Viscosity when choosing a gear oil?

2. Since Pentosin is rated at 7.0 to 7.5 cSt@100C, and Motul is rated 15.2 cSt@ 100C, does that mean I would be safe choosing any of the fluids between those ranges on that list?

Thanks in advanced!

 

[tc1446]

FWIW, Polaris makes a Synthetic GL-3 75-90 transmission fluid for use in the Slingshot GM manual xmsn. Not much GL-3 to be found anymore. May not have any bearing at all on the Scion, but the Aisen? transmission used in the Slingshot calls for GL3 because of "yellow metals" that supposedly the higher rated fluids might be harmful to. Just repeating what I read last year when I was searching for a Syn GL-3. The stuff costs about $12 quart at Polaris dealer. GM makes a GL3 that is conventional.

 

[RyanY]

I think it would be worth emailing Redline about their MT-90 gear oil. It is GL-4 (safe for yellow metals) and the rep would likely have further info on compatibility with your application. Their products are awesome, but overkill for most street applications except towing or high performance.


https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

 

[RooflessVW]

Is something inherently wrong with the Toyota fluid?

 

[RyanY]

I would also consider Amsoil's GL-4 product (https://www.amsoil.com/shop/by-prod...ransaxle-gear-lube-75w-90/?code=MTGQT-EA) but, as with Redline, it is probably overkill. However, if you're looking for the best and having some shift issues, this may be worth trying. I'm sure other, less expensive, products will work fine, too.

 

[ARCOgraphite]

Originally Posted by rooflessVW
Is something inherently wrong with the Toyota fluid?
Factory intall and what the dealer sells are 2 different things often. And the Jopbber stuf is sometimes way inferior. Like the Mobil HD85W90 they put at 36K service into my Nissan Rogue X -axle and rear dif, Fairr during summer but what a drag in the winter.

 

[Ded Mazai]

My experience with my Subaru BRZ gearbox oil. The gearbox was replaced under warranty and the dealer put a 80W-90 GL-5 (unknown brand). The car became not drivable. At -10 or -15 degrees I was not quick enough to change to the 2-d gear before the car came to a stop. The resistance drag was enormous. I asked the dealer to follow the manual and use the proper oil. They changed to a 75W-90 GL-5 (unknown brand). Much better but still I did not like it. And I did not like the fact it was a GL-5 oil. So I changed by myself to a motor oil Amsoil 4x4 0W-40 with no friction modifiers. So much better shifting, about the same as with the factory oil. Everything was fine until about 1 year on the oil: the shifting started to become harder and harder. I replaced the oil to Amsoil 75W-90 GL-4. This is what I still have in my car. I would say Amsoil is Ok but not close to the factory oil. It is thicker. For the summer it is fine but not in the winter. Better than the dealer's 75w-90 GL-5 but not much. I am planning to use a Pennzoil Syncromesh oil for my next change. It is a 10 cSt oil, GL-4. I have read good reviews from the people who use it in BRZs.

 

[Ded Mazai]

Originally Posted by rooflessVW
Is something inherently wrong with the Toyota fluid?


It is not available outside of Japan.

 

[nicknak]

Originally Posted by nicknak
1. Are there any other factors to consider besides Kinematic Viscosity when choosing a gear oil?

2. Since Pentosin is rated at 7.0 to 7.5 cSt@100C, and Motul is rated 15.2 cSt@ 100C, does that mean I would be safe choosing any of the fluids between those ranges on that list?


Does anyone know the answers to these questions?

Originally Posted by tc1446
FWIW, Polaris makes a Synthetic GL-3 75-90 transmission fluid for use in the Slingshot GM manual xmsn. Not much GL-3 to be found anymore. May not have any bearing at all on the Scion, but the Aisen? transmission used in the Slingshot calls for GL3 because of "yellow metals" that supposedly the higher rated fluids might be harmful to. Just repeating what I read last year when I was searching for a Syn GL-3. The stuff costs about $12 quart at Polaris dealer. GM makes a GL3 that is conventional.


That's interesting. Do you know if there is a VOA on this stuff?

Originally Posted by RyanY
I think it would be worth emailing Redline about their MT-90 gear oil. It is GL-4 (safe for yellow metals) and the rep would likely have further info on compatibility with your application. Their products are awesome, but overkill for most street applications except towing or high performance.
https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil


I used to use Redline in my WRX. I'd be willing to consider them, I've just heard mixed opinions on using it in the FR-S/BRZ.

Originally Posted by rooflessVW
Is something inherently wrong with the Toyota fluid?


Like Des Mazai said, you can't get it, and it's also apparently terrible:
https://www.ft86club.com/forums/showthread.php?t=46208

Originally Posted by RyanY
I would also consider Amsoil's GL-4 product (https://www.amsoil.com/shop/by-prod...ransaxle-gear-lube-75w-90/?code=MTGQT-EA) but, as with Redline, it is probably overkill. However, if you're looking for the best and having some shift issues, this may be worth trying. I'm sure other, less expensive, products will work fine, too.


The car's current fill is actually Amsoil, but it's a bit old. Not many miles, but might be 2 years old. I just bought the car, and it was used as an occasional Summer time only lapping / hpde day toy. He's put less than 1000 miles on the car I. The last 2 years.

 

[nthach]

Originally Posted by rooflessVW
Is something inherently wrong with the Toyota fluid?

It's a Subaru actually

I have little experience with Subaru gearboxes, from what I've read there's guys on NAISOC and the WRX forum who like Red Line and Motul fluids, while others prefer Subaru's own Extra-S oil. SOA no longer sells Extra-S, it's now an Idemitsu of America oil in a Subie package. But further Google-fu also led me to this - Subaru uses two different fluids from the factory, there's also an Extra-MT for the newer 6-speeds.

It seems like the Extra-MT is a GL-4 oil like Red Line MT-90 and Toyota's GL-4 75W-90 that isn't available in the US.

In this case, it wouldn't hurt to experiment and see which one feels right to you - unlike an automatic where the wrong fluid might be doom and gloom for the clutch packs and torque converter clutch, manuals aren't that sensitive to the "wrong" fluid unless your synchros are made from an exotic material like carbon fiber.

https://www.flatironstuning.com/p-2849-subaru-high-performance-gear-oil-75-w-90-the-new-extra-s.aspx
https://content.subarunet.com/snet/...emicals/sheets/soa748v0100_sellsheet.pdf
https://forums.nasioc.com/forums/showthread.php?t=2777257
https://forums.nasioc.com/forums/showthread.php?t=2809891

 

[nicknak]

I've read that the transmission is a Toyota unit, not a Subaru, and it more akin to the unit in the Honda S2000.

I'm tempted to try the Honda MTF since the Kinematic Viscosity is closer to the Pentosin that many people love for these cars. The biggest difference though, is the Honda MTF is a semi-synthetic.

 

[SatinSilver]

When some of the Honda v6 manuals had a crunch when changing gears they came out with a tab to use AC Delco Friction Modified mtf. The FM part is the important thing when ordering since there's a non-FM version. Thanks!

 

[RooflessVW]

Originally Posted by nicknak
I've read that the transmission is a Toyota unit, not a Subaru, and it more akin to the unit in the Honda S2000

And the Miata. And the RX-8.

It's a Toyota TL70 - a variation of the Aisin AZ6 made specifically for the twins.

Run the OEM fluid. Or Honda MTF. Or 10W-30. Or Delvac 75W-90. Or Syncromesh. Or ATF.

Personally I'd pick up some oil from Toyota - it will restore the smooth action of the shifter. Change it again when it gets notchy.

 

[nicknak]

Originally Posted by nthach
In this case, it wouldn't hurt to experiment and see which one feels right to you - unlike an automatic where the wrong fluid might be doom and gloom for the clutch packs and torque converter clutch, manuals aren't that sensitive to the "wrong" fluid unless your synchros are made from an exotic material like carbon fiber.



So it's safe to try out other fluids? Can I just try something out, and if it doesn't feel good, try something else?

Do I need to pay attention to cSt rating? I thought I read if I go too thin, I risk prematurely wearing out the transmission and syncros, but if I go too thick, I would only reduce the efficiency i.e. mileage / hp?

How do I know if I'm doing damage to the transmission? UOA


Thank you!

 

[RyanY]

You mentioned that the current fill is amsoil, but in your first post you mentioned that it shifts kinda hard. If the current shifts are tolerable, just leave the amsoil in for a few more years (another 30+ k miles). Otherwise look for something that shifts better. I would start with redline, but other yellow-metal-safe fluids also exist (eg, Pennzoil synchromesh).

 

[nicknak]

Yes, it's old Amsoil. I'm changing the fluid because it's old, doesn't feel great when cold, and I'd like something fresh before I start racing / autocrossing it.


Thank you everyone for your suggestions. I'm still not getting an answer to my question though. Maybe I'm not asking the right questions. I'm not asking for specific fluid recommendations. I'm asking what specifications, like viscosity, additives, etc., do I need to pay attention to when trying to pick a fluid that would work with my transmission? Do I only need to make sure the fluid is in the same cSt range as stock, or is there more to it?