The type of oil you use depends on the use of your Lex, that ist weather conditions and if it´s tuned or not.
I have had goed experiences wil Castrol of Mobil 1 5w 30, 5w 40 or 5 w 50 all fully synthetic,
the 0w 30 was imho a bit too thin but could also be an option.
Basically I thing every oil between 0w 30 and 15w 40 is ok as long as the api sl approval is there and it´s branded.
Difference between 0w-5w and 10w and up is that the car starts better at lower temperatures and the motor ist lubracated much faster after a cold start, especially the difference between 5w and 15w is too big and my car ran a lot better after removing the new 15w40 oil the garage put erratically in it and exchanging it for 5w 40.