75w

[Aaronj95]

Hello, thanks for having me here! I have a 2014 Corolla 6mt that calls for 75w for the gearbox, could I go to a 75w80 without any negatives? Thanks!

 

[Lubener]

That will work as well as a 75w-90 gear lubricant which might be easier to find , provided your gearbox calls for a GL-5 lubricant which might cause issues with bronze parts if there are any in your Corolla's gearbox.

 

[Aaronj95]

It actually calls for a gl 4

 

[Jetronic]

Hello, thanks for having me here! I have a 2014 Corolla 6mt that calls for 75w for the gearbox, could I go to a 75w80 without any negatives? Thanks!

That's not straightforward to answer.

The gears and differential, aswell as the bearings will love a higher viscosity oil, but there's a potential issue with the synchro's. Synchro's operate slower with more viscous oil. That's why a lot of MT operate worse when it's cold, after the first start.

If the synchro's are up to it, I would always try to go with a 75W-90 GL-4. That is assuming you intend to keep the car as long as it's economically viable.

 

[Kira]

The OP joined yesterday.
I'm not on the Welcoming Committee....but WELCOME!

It sounds like you might not be aware that certain Sulphur compounds have adverse effects on "yellow metal" parts like brass and bronze; both commonly used in gearboxes.
GL-4 lubes don't have it <use GL-4 in gear boxes.
GL-5 lubricants do <use GL-5 in axles and differentials.

 

[Astro14]

Why not use a 75W?

My Volvo (type 2004 V70R) with a manual calls for a 75W. Lots of good options.

I currently run HPL 75W (it’s not on the site, https://www.advlubrication.com/ but if you call them directly, they have it, oh, and tell Mary Jane I said Hi!).

There is also Ravenol MT 75W oil, available from lots of sources, including Amazon: RAVENOL J1C1003 MTF-3 SAE 75W Full Synthetic Gear Oil - 1 Liter for Manual Transmissions, Differentials & Transfer Cases https://a.co/d/hqR4Xxe

Or, Liquimoly, also on Amazon: Liqui Moly Top Tec MTF 5100 SAE 75W | 1 L | Gear Oil | Hydraulic Oil | SKU: 20352 https://a.co/d/3ifpJL1

I mean, sure, it won’t “hurt” anything to substitute, but the trans probably won’t shift as well when cold.

Why not use something that meets the exact viscosity specification and is designed for a manual transmission?

 

[dnewton3]

Whatever you choose, brand and grade, do NOT use a GL-5 where GL-4 is spec'd.

 

[Snagglefoot]

Redline MT 85. It’s a GL4 75w85. Castrol also makes a MT GL-4 75w90.