Even if it were 5w40 (which its not) it wouldn't make any difference. 40 is the weight the oil is at running temperature, in summer you could probably even have straight 40 (if you could get it) like old times. The 5w 10w is the winter rating, the viscosity it manages at a low temp and even 5w-40 and 10w-40 are virtually the same down to 0c.
Again in my humble opinion. Any decent synthetic based 10w40 changed to a good schedule will be good. There's nothing magic in selenia, when fiat sell the diesel engines to GM do vauxhall/ opel owners get recommended selenia? no, they get recommended gm oil. Fords that use the 1.6 peogeot diesel engine have ford oil yet if you service a citroen with the same engine then, youre told you Must use some total oil they recommend. I think there's a a theme here. Manufacturers have deals with oil companies that they recommend and use, it doesn't however normally anything that special, just the right oil in the brand they are pushing. The correct spec for your oil is in the handbook, whatever you choose as long as you keep to that may as well be down to to what's the nicest bottle or what brand you feel most assured with.
