Subaru put Extra-S GL-5 trans fluid in 2013 BRZ (grind/clunk 3rd to 4th)

[SockMonkey]

So I picked up a '13 BRZ with 59k miles a few weeks ago, obviously outside the 5yr/60k drivetrain warranty. After getting use to the car I started to notice a crunch/grind when I was shifting 3rd to 4th at higher rpm, like a highway on ramp. After some googling I found this was/is a some what common problem, usually fixed be replacing the tranny. I figured it needed a fluid change, but remembered the previous owner saying they had it serviced last year. I got him to send me the invoice and it says 3 quarts of "SOA427V1700 HIGH PERF GEAR OIL 75W-90". When I google that, I find that it is Subaru's oem oil and it is a GL-5 gear oil. Everything I read says these transmissions should only ever have GL-3/4 because GL-5 fluids have sulfur and phosphor additives that are bad for the synchros. This was done at 51k, 8k miles ago.

I was originally planning to change the fluid for some redline MT-85 or 90. But before I do that, would I have any grounds to pursue repair/replacement from Subaru? Could having that gear oil in there for 8k miles have caused this crunch I'm experiencing from damaging synchros?

[86league]

The newer manuals state GL-4/5 is acceptable :

Use either of the following:
• “MG Gear Oil special II”
• Other gear oil that meets API GL-3, GL-
4, or GL-5 and SAE 75W-90 specifications

Earlier manuals are less clear but I suspect that "or upper grade" may mean GL-4/GL-5?:

Use either of the following:
• “MG Gear Oil special II”
• Other gear oil that meets API GL-3 or
upper grade and SAE 75W-90 specifications

Did they actually change materials synchros from the earlier versions to make them GL-5 compatible?

I know they shot-peened the gears for MY2017+ to make them slightly more robust along with the bump to 205 HP , but am unaware of other major changes.

[SockMonkey]

Thats interesting. According to a thread I just read, the 2017+ transmission appears to be identical. Hmm.

Seems like relatively common knowledge that the additives in GL-5 are bad for yellow metals, yet they recommend using it... Was GL-5 a thing in 2013?

[Oxyg3n]

I have the exact same question. Looking to use all OEM fluids for both tranny and diff but Subaru only sells GL5.

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[Setgo]

You can try to talk to subaru for a replacement. I doubt they would replace it for free. In terms of fluids, there are forum posts within the past week about which fluids people have decided to use. Ultimately, if you change out the fluid, it might solve the problem but i personality think once it starts to grind, it will always grind. Replacing a transmission is pretty cheap for our platform. Buying a used transmission ranges from 250-500$

[vicious_cb]

From the 2020 Toyota Manual

■Differential*:
Oil capacity (Refer-ence)1.20 qt. (1.15 L, 1.01 Imp. qt.)
Oil type and viscosity*• Toyota Genuine Differential Gear Oil LX• Other LSD gear oil that meets API GL-5 and SAE 75W-85

*: Your Toyota vehicle is filled with “Toyota Genuine Differential Gear Oil” at the factory. Use Toyota approved “Toyota Genuine Differential Gear Oil” or an equivalent of matching quality to satisfy the above specification. Please con-tact your Toyota dealer for further details.

■Manual transmission

Gear oil capacity (Reference) 2.3 qt. (2.2 L, 1.9 Imp. qt.)
Gear oil type and viscosity: Use either of the following:
• “TOYOTA Genuine MG Gear Oil special II”
• Other gear oil that meets API GL-3* and SAE 75W-90 specifications
NOTICE
■Manual transmission gear oil: Using a manual transmission gear oil other than “TOYOTA Genuine MG Gear Oil special II” may cause occurrences of rattling noises while idling and poor fuel consumption.Never use different brands together.

■Automatic transmission

Fluid capacity*7.9 qt. (7.5 L, 6.6 Imp. qt.)
Fluid type TOYOTA Genuine ATF WS
*: The fluid capacity is provided as a reference. If replacement is necessary,contact your Toyota dealer
■NOTICE Using automatic transmission fluid other than “TOYOTA Genuine ATF WS”may cause deterioration in shift quality, locking up of your transmission accom-panied by vibration, and ultimately damage the automatic transmission of your vehicle.

The 2020 manual only lists GL-3 for the tranny. I thought the Subaru and Toyota tranny were identical?

[Oxyg3n]

Originally Posted by vicious_cb

From the 2020 Toyota Manual



The 2020 manual only lists GL-3 for the tranny. I thought the Subaru and Toyota tranny were identical?

Does Toyota sell OEM GL3 oil? Since Subaru sells only GL5 OEM and manual for my 2017 Brz lists GL5 as an acceptable option.

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