Since my Mazda is no longer under warranty its on 5W-30 it has made zero difference and over that extended period there is zero change in my MPG vs 0W-20.
Yes my Mazda has one for the transmission but you have to remove the air box to get to it. Isn't that just handy part of the planned obsolesce program of modern car manufacturing!
Well at least you have a chance to get an oil filter with better efficiency than you would likely get at the Oil change shop or Stealer ship. On a synthetic change my cost is usually 1/3 the Stealership cost and with better oil and filter.