Unless you are getting below -25F then it won't make any difference, especially until -30F or below. So use either one in that case. At 0F there will be no meaningful difference.
Mercedes does not specify a required grade, that it is only a recommendation. They require an approval and as long as that is met so will any warranty requirement.
As far as shear stability is concerned that has a lot to do with how shear prone your engine is and the quality of the VII used in the formulation. In order to meet the Mercedes approval requirements any oil that carries the required approval will be acceptable.
For most applications just pick the least expensive oil you can find at Walmart or Amazon that carries the approval required by Mercedes. Make sure it actually has the approval and isn't just "recommended for". The labeling requirements as well as all the approved oils can be found here:
https://bevo.mercedes-benz.com/bevolisten/229.5_en.html
Mercedes does not specify a required grade, that it is only a recommendation. They require an approval and as long as that is met so will any warranty requirement.
As far as shear stability is concerned that has a lot to do with how shear prone your engine is and the quality of the VII used in the formulation. In order to meet the Mercedes approval requirements any oil that carries the required approval will be acceptable.
For most applications just pick the least expensive oil you can find at Walmart or Amazon that carries the approval required by Mercedes. Make sure it actually has the approval and isn't just "recommended for". The labeling requirements as well as all the approved oils can be found here:
https://bevo.mercedes-benz.com/bevolisten/229.5_en.html