- Joined
- Oct 16, 2023
- Messages
- 265
When I look up the spec it says I can use a gl5 75w90. Does that sound right? I thought gl5 was a no no in manual transmissions but maybe I'm mistaken. What would you run in this application?
Manual transmission fluid for 2021 wrx
- Thread starter Orangepeel
- Start date
Motul Gear 300 is the only fluid to use in a Subaru AWD manual transmission. Remember that the manual transmission is combined with the front diff.
My ECHO says either GL-4 or GL-5, and I’ve used both. I prefer a dedicated MTF from either Amsoil or Redline but both work.
Last edited:
- Joined
- Oct 16, 2023
- Messages
- 265
I guess I was concerned a gl5 wasnt good for the transmission but I guess it's totally fine?
Ive had FWD cars that spec GL-5 for the manual transmission. Key is to use one that is the proper viscosity, most diff fluids are too high in viscosity for proper syncro action.
Indeed incorrect.
"Subaru recommends the use of Subaru Extra MT. As alternative GL-5 SAE 75W-90 may be used, however using this type of oil will detract from driveability and fuel efficiency. "
Modern synthetic GL-5 will not harm a MT. (old school 1950 SAE 90 MIGHT)
A couple choices. I ran Amsoil 75W-110 in my old school trash MT 5 speed 2014 WRX. VERY weak transmission/transaxle, would shear lubes and gear teeth. Different subject.
For yours you have some choices - somewhat climate dependent.
HOT places:
https://www.amsoil.com/p/amsoil-severe-gear-75w-90-100-synthetic-gear-lube-svg/?zo=515729
https://www.amsoil.com/p/amsoil-severe-gear-75w-110-100-synthetic-gear-lube-svt/?zo=515729
In between, but GL4: https://www.amsoil.com/p/amsoil-75w-90-manual-transmission-transaxle-gear-lube-mtg/?zo=515729
Cold location (and actually closer to Subie recommendation):
https://www.amsoil.com/p/amsoil-severe-gear-75w-85-100-synthetic-gear-lube-svl/?zo=515729
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
It won’t cause damage. There an old concern no longer applicable.
Historically you need a GL-5 in Subaru transmissions because the front differential is also in there and it needs EP additives.
Historically, shifting on Subaru transmissions has also been kinda **** as a result.
I am not up to date but I would be careful using anything that’s GL-4 only.
Historically, shifting on Subaru transmissions has also been kinda **** as a result.
I am not up to date but I would be careful using anything that’s GL-4 only.
Gl5 in trannies has been findfor 20+ years.
As far as eating yellow metals yes. It is still more difficult to make a transmission and fluid combo shift well when the fluid also has to have EP additives.
At least Subaru struggles with it historically.
At least Subaru struggles with it historically.