What's the best gearbox and diff oil for a 130,000 mile car?

There is an occassional whine, mainly when I put it into first going slowly from a higher gear, all the gear changes are smooth, forgot to say it's a 1997 uk turbo.

Seperatley, I am looking to run about 350bhp and similar torque next year and was wondering, what is the best option, to get mine rebuilt to cope or buy a stronger second hand one?

Thanks

 

6 speed from an STI or 5 speed from a Blob / Hawk WRX

 

What oil should I be using at the moment?

 

https://www.scoobynet.com/856482-opi...-50-off-2.html