Hi, my S2 should be of the road soon after a bottom end and head rebuild, after shelling out over £1000 in the last 4 months, i was wondering what the best oil to use while i run it in, then after i run it in what oil to use.

I have sum Mobil 1 5-50w Rally synthetic oil at work which i can get for a fiver for five litres cause its discontinued at my work, not sure if its ok?

Car will be low comp running 21 psi, etc etc.