Hi, sorry if these questions have been asked a few times before but it's stupid o clock in the morning and I'm very tired. (At work so can't get to bed yet).

Could somebody please let me know which oil I should be using, I know it should be fully synthetic 10-40w. But is there much difference between makes?

The diff oil is due for a change but not sure what should go in?

Plugs are ready for a change, but had it rolling roaded a few months back and was told the plugs are ok but starting to break down at about 8000rpm so could do with slightly upraited plugs? Does anybody know which are best?

Car is a year 2000 Sti (version 6) with 45000 miles on it and all standard exept exhaust.

Thanks in advance for any help.
Adam.