Just to add.
My last van a transporter 2.5, 4 years old less than 45k on the clock developed a starting fault. VW reported back that it was a suspected cylinder head issue. £4k repair minimum, £7.5k worst cast scenario.
After a lot of heated arguements with Volkswagen they blamed the damage on bad fuel. I always use Shell, however I was the second owner and for half of its life I honestly don't know what the previous owner used to fill her up. Anyway to cut a long story short I had the van out back together and sold it on.
Since buying the California I always use Shell, unless abroad as that was the fuel Volkswagen recommended to use in my last van. Funny how this stuff is never stated when people buy the vehicles, but crop up should a fault occur...???