'08 WRX. Temps here run 15*C~35*C. I've been running Redline 75W90 MT-90 for 50,000km and just started to get grinding going into second. I just changed the tranny fluid 10,000km ago.
I can get Redline shockproof and Shell Spirax 80W90 which it seems is an acceptable alternate to the Castrol.
Castrol Hypoy C, 80W90 and Pennzoil 75W90 Synchromesh are are unavailable to me. I can get Agip, Repsol, Pennzoil, Torco or Valvoline 75W90 synthetics but I'm guessing they're only as good or bad as the Redline.
If it's the synthetic nature of these fluids that's the issue I can however get non-synthetic Torco MTF, or some off-brand 75W90 or 80W90 dino gear oils.
Suggestions as to which would be better to finish off a cocktail? I still have 2qts of Redline 75W90 left over.