Red Line 75W90NS GL-5 Gear Oil in the Trans - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

venturaII · 04-23-2018, 09:37 PM

Quote:

Originally Posted by j3rf

Continuing this discussion, Motul's product sheet says "Suitable for any type of seal and yellow material used in gearboxes design. "

Then use it. Maybe you'll get lucky.

ajh88 · 04-24-2018, 09:21 AM

Quote:

Originally Posted by venturaII

GL5 is used in the differential. GL3/4 is fine in the transmission.

The GL-5 that I bolded and quoted is specifically in the "Manual Transmission" section that discusses fluids. The Differential fluid is a different section.

venturaII · 04-24-2018, 10:11 AM

I realize that, and unless Subaru/Toyota/Aisin did something different in the transmission starting that year, I'd be willing to bet it's an error. Even buffered GL5 extreme pressure additives won't protect the friction cone area of a syncro.

sly · 05-06-2018, 05:39 PM

parts.subaru.com lists every part for the 2016 and 2017 manual transmission as identical. I can find no difference between the transmissions.

Either the manual is in error and you shouldn't use GL5 in the transmission or you can use it in any model year. There is nothing special about the 2017 that makes it able to use GL5.

Lynxis · 05-07-2018, 11:05 AM

From the Subaru manual:

"• Other gear oil that meets API GL-3 or
upper grade and SAE 75W-90 specifications"

If you ask Subaru for fluid, they will give you the same GL5 based fluid for the Trans and the diff for a MY13 car.

Coheed · 05-12-2018, 01:45 PM

Gear oils have seen declines in sulfur content since the 90s and many have been used in transmissions like ours without issue. Molybdenum disulfide is the high pressure additive used iirc. Sulfur is corrosive to brass.

Not all gl4 work great for brass synchro either. Best to find a gear oil specifically designed for high performance with brass. Too slippery and gears will grind. Shifts will be stiff. Too abrasive and you'll wear synchro prematurely.

Do people try using BMW mt fluid? Or porsche?

04-24-2018, 10:11 AM	#17
venturaII Only users lose drugs. Join Date: Nov 2014 Drives: All the time Location: Shrewsbury upon Worcestershire Posts: 1,819 Thanks: 874 Thanked 1,067 Times in 674 Posts Mentioned: 3 Post(s) Tagged: 2 Thread(s)	I realize that, and unless Subaru/Toyota/Aisin did something different in the transmission starting that year, I'd be willing to bet it's an error. Even buffered GL5 extreme pressure additives won't protect the friction cone area of a syncro. __________________ "To know a thing well, know it's limits. Only when pushed beyond its tolerances will true nature be seen." Amtal Rule

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05-06-2018, 05:39 PM	#18
sly Senior Member Join Date: Dec 2015 Drives: 2016 Cosworth 2.2 BRZ Location: TN Posts: 302 Thanks: 81 Thanked 185 Times in 112 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	parts.subaru.com lists every part for the 2016 and 2017 manual transmission as identical. I can find no difference between the transmissions. Either the manual is in error and you shouldn't use GL5 in the transmission or you can use it in any model year. There is nothing special about the 2017 that makes it able to use GL5.

05-12-2018, 01:45 PM	#20
Coheed Senior Member Join Date: Jun 2012 Drives: DGM BRZ Limited Location: Seattle Posts: 813 Thanks: 209 Thanked 225 Times in 157 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Gear oils have seen declines in sulfur content since the 90s and many have been used in transmissions like ours without issue. Molybdenum disulfide is the high pressure additive used iirc. Sulfur is corrosive to brass. Not all gl4 work great for brass synchro either. Best to find a gear oil specifically designed for high performance with brass. Too slippery and gears will grind. Shifts will be stiff. Too abrasive and you'll wear synchro prematurely. Do people try using BMW mt fluid? Or porsche?

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