There are very opinionated posters in the 5W-20 discussions here. There seems to be a consensus that there are a couple of things about this oil and the engines that are supposed to use it. 1) It appears the engines are no different than the engines that were specced for 5W-30 oils the model years before, and that the same engines that call for 5W-20 in the U.S. call for higher visc oils in other countries (and in higher performance models using the same engines) 2) No incidences of higher wear or failures have been attributed to the use of 5W-20, and it appears to give as good of service as higher viscosity oils. 3) There may be a mild fuel savings using 5W-20 oils, without any apparent negative results. 4)Many 5W-30 oils shear down to near 5W-20 fairly quickly, so the advantages of using it decrease. So why not use 5W-20 oils in 5W-30 applications?