Mingin
Flood Motorsport install a type of Gear Box oil that is cheaper than Redline LWSP and is much better on syncros’s. I use it today in my 12.8 sec 5 speed MY99 that has survived hundreds of smoking launches with original GB! I used the RL LWSP for several years then flipped to "Tony's love lube" about 2 years ago. It’s his "top secret" fix it oil.

If a Subaru dealer uses a different oil to solve your problem whilst under warranty be very, very careful...they have a huge conflict of interest. i.e. they do not want to spend big $$ repairing your gearbox/diff. Diluting the GB oil with Auto Fluid sounds suss to me.

I agree, you have tried your best to look after the car. Unless you have had the misfortune of Polarbear test driving it before you bought it either way it sounds like you may need repairs. Not sure how far out of warranty you are but consider escalating your complaint to Subaru Australia after having a professional like Tony Flood check your car over.