I am changing my transmission fluid (mk5 6spd manual) and I've discovered the drain and fill holes require a tamper resistant torx bit to remove them. Does anyone know what size Torx bit I will need? I've tried T55 and no luck (too small).

Not sure off hand, but I have one myself. I can check when home if you still need to know.
You're welcome to borrow it if you like. I'm in east Auckland.

16mm triple square. (Not torx).

This is the one I have:

https://www.autotrail.co.nz/shop/hand-tools-2/sockets-ratchets/torx-bit-sockets/koken-4020-60-xzn-bit-socket-with-hole-1-2dr-mh16/

Quote from: The Red Warrior on June 18, 2025, 08:27:15 PM16mm triple square. (Not torx).

This is the one I have:

https://www.autotrail.co.nz/shop/hand-tools-2/sockets-ratchets/torx-bit-sockets/koken-4020-60-xzn-bit-socket-with-hole-1-2dr-mh16/

Thank you, I think I worked it out and as you say it's not a Torx at all. I found a bit similar to your one on the Sulco website. It hasn't arrived yet but the description says it's specifically for VW transmissions.

https://www.sulco.co.nz/1-2-Dr.-M16-Tamp.Spline-Socket-VWandAudi

Quote from: The Red Warrior on June 18, 2025, 09:55:49 AMNot sure off hand, but I have one myself. I can check when home if you still need to know.
You're welcome to borrow it if you like. I'm in east Auckland.

Thank you, I think I worked it out and I'm waiting for the courier to arrive.

https://www.sulco.co.nz/1-2-Dr.-M16-Tamp.Spline-Socket-VWandAudi

All good. Just saw your same question on Mk5 Golf GTI forum too 👍