2013 Subaru 2.5 na engine. Used group III in 0& 5-20 for a few yrs w/o issue. Switched to group 4 Amsoil 0-20 for the past 2 yrs. Oil consumption of a few qts between oci. Bit of a short tripper vehicle. UOA last yr for one yr oci resulted in oil being fine but with a few qts oil added. My remedy... added one qt of Pennsoil 5-20 with the Amsoil and now NO consumption at all! Problem solved. What do U all think?