http://www.ebay.co.uk/itm/10w-40-GENUINE-GM-VAUXHALL-SEMI-SYN-ENGINE-MOTOR-OIL-5L-/150736821955?pt=UK_Vehicle_Oils_Lubricants_Fluids&hash=item23189d5ec3#ht_795wt_698

Is there any reason why this oil would not be suitable for use in my SDI?

It makes no mention of being certified to any VW oil standard for starters. You can get Quantum (VW's own brand fully certified oil) from TPS for less money last time I checked and they probably have a location near you.

Nearest TPS to me is 20 miles away. If a had a PD engine I wouldn't shift off the VW oil.

I think the SDI requires 10W40 conforming to VW 505 00 spec, most of which on the market are semi synthetic. My guess is that the oil you quote on ebay would be fine since the SDI is a fairly bog standard diesel engine. If you want to be absolutely sure then your cheapest option would be a bottle of quantum platinum from TPS.

20 miles in a car that's doing over 60mpg can't be much of an issue surely when you're paying over the odds for delivery even if it's 'included' in the price? If it is then ECP or your local motor factor will be able to get you the correct oil and should be equally cheap, or one of the many on-line stores such as Opie Oils etc, wherever you order from get oil that meets the VW spec as indicated in the hand book, the cost difference will be minimal and it's not something you want to get wrong.

*edit* Just checked my handbook and it's VW505.00 for the SDI as Piggoy suggests.

20 miles in a car that's doing over 60mpg can't be much of an issue surely when you're paying over the odds for delivery even if it's 'included' in the price? If it is then ECP or your local motor factor will be able to get you the correct oil and should be equally cheap, or one of the many on-line stores such as Opie Oils etc, wherever you order from get oil that meets the VW spec as indicated in the hand book, the cost difference will be minimal and it's not something you want to get wrong.

I think Opie have a sale on the moment too - at least until the end of today.