Fully synth ep75w90 is what i use from these guys. 3.1L
https://www.westwayoils.co.uk/
but we have the opie oil rep on here who might be able to give a club discount. They have some good lube.
i'd personally get a new back door fix the arches and swap the fuel lid. The car would instantly be worth a sh!t load more.
what's the inside like? I'm just doing up another SDI right now. Sourced a new drivers seat cover from Germany (passenger side over there). You'd love a Lupo 3L steering wheel. Ok, so i would, but they're rocking horse poo over here and stupid money in Germany.
oh, and I was out today cruising at 80- rev counter reads exactly 3000 at that speed, so you can do gearbox ratio tests.