Spriax X Shell Gear Oil question

[Scott.T]

One for the oil experts........

Checked my gear oil a few weeks back and found it was very very runny almost like water when the box was 'town driven warm'.

Have checked the service history and Triangle Subaru put 'Shell Spirax X' in on the 30,000mile service (Car had covered 25,000 at the time).
Car has now done just over 35,000 miles

There's no viscocity recorded on the parts/material invoice but googling seems to show it's 75W/90.

Just a bit concerned as to how thin it was when warm. It does thicken up a bit when cold.
When warm the box (STi Type UK, 2007, 6-speed) does have an over-run whine/buzz that is louder than what I am used to on the Classic 5-speed. Maybe they all do that ????

Shell Spirax is not one that I have yet found recommended for the Sccob !!!!!

[DukeBoy]

Use the same viscosity in mine all be it Millers CRX 75W90 NT and have the same noise in the same box