Cheers Tim, i'm gonna go for the 5w40 castrol edge.Your car can use a 5w-30 VW507.00 spec oil or a 5w-40 505.01 oil as it doesn't have a DPF (to my knowledge, it's too early for a Seat to have a DPF). What those sites are doing is recommendind the latest spec on the basis that it's also fine for earlier cars, and yes that's fine to do, but if the car gets harder than normal use, I'd go for the 505.01 oils as they are a little thicker.
Only 3k miles a year? I would suggest that at least once a month you drive far enough/long enough to get the engine good and hot, so that any moisture that condenses in the engine will boil out of the oil. 30 miles or so ought to be enough. But this is necessary for any car which is used for short commutes, where the engine normally doesn't get very hot for very long.just done a service using Castrol Edge 5W-30 but i first used Forte Diesel Engine Flush which is class the Leon TDI 150 (ARL) has done 49k, Question is with me doing only 3k a year would you still change the oil every 12 months and would you use a Engine flush every time? this is my first Diesel as i did the oil changes on my old car every 12 months which was Petrol.