Thanks mister2 - yes, it's GL-4 rated,  which is why I chose it.
That spec sheet is actually the "heavy duty" version for trucks, etc.  400,000km change interval - whoa.  

xez 400,000km change interval - whoa.  

 
Well… you know some people don't change their fluids as often as they should!
 
But back in the NOT 'heavy duty' world, it appears that Castrol Syntrans 75W-85 has taken the place of 75W-90… and that's still GL-4 too:
 
Castrol Syntrans 75W-85 is suitable where the following performance levels are specified:
API GL-3, GL-4
SAE 75W-85; Suitable in place of SAE 75W, 80W, 75W-80, 75W-90

Thanks so much for this responnse.
Hahaha, nah man I ain't no oil chemist, just what I read and wondering if it was right.
Matter of fact the guy (previous owner) did put GL-5 in there... :|
 
Is that it? Goodbye syncros?
 
EDIT: Replying to Falcon, who said GL-5 is bad for syncros lol

Just spoke to the previous owner.
He said GL-5 is what Toyota recommends.
RIP.
 
Here is prayer the syncros haven't given up on me... yet.
 
EDIT: He searched up the wrong gearbox: E153... sigh.

Falcon
empty out whatever is in there and refill with DEXRON 3.Auto Trans Fluid. (Penrite have excellent products).

Is this it?
autobarn(dot)com.au/penrite-atf-dxiii-4-ltr-atfdx3004

Yes. That is the correct stuff.  Fill with that and drive it for a few hundred km.  Take note whether the gear shifting improves.  IF it does I will then recommend another GL4 oil for you to try.
I have managed to save two gearboxes that had been playing up after using bloody GL5 oil.  Ive had several more that did NOT improve and had to be stripped and reconditioned.
Pay close attention to the clutch to check that it is fully disengaging as it can cause a lot of harm to the syncros.
You can PM me if you need to know how to check the clutch operation.

andezzat, I hope you have good luck with your synchros, and you may be interested in this:
 
http://www.widman.biz/uploads/Transaxle_oil.pdf

Thanks so much guys.
 
I've only driven it for barely anything right after the oil change, it's still pretty ****ty. Rev matching in neutral is fine though, like butter.
 
Falcon I'll PM you, I'm a bit of a noob.
 
Reddtarga, I read bits of that article before, it's pretty interesting. Thank you for mentioning it anyway.

Falcon
Yes. That is the correct stuff.  Fill with that and drive it for a few hundred km.  Take note whether the gear shifting improves.  IF it does I will then recommend another GL4 oil for you to try.
I have managed to save two gearboxes that had been playing up after using bloody GL5 oil.  Ive had several more that did NOT improve and had to be stripped and reconditioned.
Pay close attention to the clutch to check that it is fully disengaging as it can cause a lot of harm to the syncros.
You can PM me if you need to know how to check the clutch operation.

I've sent you 2 PMs, they don't show in my sent messages...
I hope you received them.

Or you could just leave the ATF in there.

So many views on oils, you have quite a few choices.

Cheers