i have had a mail back from guy at opie oils and he has recommended vw503.01 motul 8100 0w-30 is this right for long life oil as i can't seem to find vw503.01 on here or is it just an old number for the same stuff

Wouldnt the easiest bet be to get the dealer supplied stuff or what GSF have? Itll save you a good few quid on postage too.

opie do it for £37 for 5ltrs inc vat + p+p

To be honest Im not sure why you want to change it half way through as you mentioned also, just switch it to a fixed interval.

well that's another ongoing debate in my head!! fixed or variable ? which is cheapest in the long run