All this discussion is like the ancient Greek tale of arguing how many spirits can dance on the head of a pin.
20W-50 oil is OK in warm to hot climates and not OK in cold temperatures, in general.
If the other weights, probably the 0W-40 made by Mobil covers all the bases most adequately, along with other synthetics more or less in similar weight ranges.
20W-50 is not ideal for the most modern engines, but in warm to hot weather I bet that most can handle it or a blend including it.
20W-50 oil is OK in warm to hot climates and not OK in cold temperatures, in general.
If the other weights, probably the 0W-40 made by Mobil covers all the bases most adequately, along with other synthetics more or less in similar weight ranges.
20W-50 is not ideal for the most modern engines, but in warm to hot weather I bet that most can handle it or a blend including it.