I think it depends if you are driving a UK or Import car as to what they use.
Scoobie Elf where are you based?
and what's your excuse for not joining CADS if you're in the Stockport area?????LOL
Might be worth phoning the garage that last serviced it, to see what they put in.
I'm not sure how fully synthetic & semi synthetic would mix in case the latter's in already.