hi everyone. This is my first post. A few questions
 

Just bought a lovely standard 1998 UK turbo 4 Dr. Not had a Scooby for about 15 years now so I have a few questions.

Should I be using higher octane fuel?

What is the best oil to use in the diffs?

Sorry if these questions have been asked often but am a bit of a dinosaur on the internet.

Looks a great forum with
lots of. Knowledgeable people on.

Yep, deffo use high octane fuel unless its been mapped to run something different.
Oil wise, give these guys a shout -

http://www.opieoils.co.uk/

use vpower or tesco 99

i think its 75w90 for box and diffs. i use redline or millers, the best stuff i can afford, be warned the top stuff is expensive

If it's a standard 98 car, it's not been mapped, end of.