Awesome car BTW. Me? I would use Redline 75W90 NS GL-5 Gear Oil. Why? Redline states it helps to slow synchros for easier shifting across a broad temperature range. That is exactly what you want in a manual transmission. Redline doesn't cheap out on the base oil in their products.
Wife: 15' Audi A4 quattro 6 speed manual
Me: 13' VW GTI 3 door 6 speed manual