Was considering running Mobil1 in my truck and car after the GC as a camparo to the GC and Amsoil that have been run previously. Both the Amsoil and the GC have a little higher Vis. and I like that. Was wondering if I could mixed one quart of truck and suv (5w-40 i think) in when I change and bring the Vis. up a litte. Any comments?