Gearbox, Diff, and P-Steer oil purchase?

[MIDZ]

Hi All, Ordered some oils last night from Opie Oils (Gearbox & Diff) and found VAG power steering fluid on ebay from VW dealer

I was going to buy the lot from Audi but after entering my reg on Castrol website decided to go for:

Diff (Syntrax Longlife 75W-90 Fully Synthetic GL-5), Gearbox (Syntrans Transaxle 75W-90 Fully Synthetic GL-4), PS Fluid Green (G004000M2)

Also cars going into Audi next month for yearly service where I supply the oil, this year I'm going to supply Castrol Edge 0W-30 instead of LL 5W-30 on the basis it doesn't do many miles a year (2.5k), and mostly stop/start rather than motorway miles

Anyone went down this route?

Cheers