I don't buy oil or gasonline based on price. I haven't since I was 17 and driving a 240,000 mile Dodge pickup.

I go here:
https://bevo.mercedes-benz.com/bevolisten/229.3_en.html

Now, the only oil I could find locally was 0W40 (too hot in Texas for that) and 5W40.
So I went with 5W40.

I won't use 0W40, it's just too thin - and MB now recommends 5W40, they APPROVE of 0W40 but they RECOMMEND 5W40.