I will use either 5w-40 or 0w-40, as it doesn't matter to me. I think everyone has their favorite oil, and the big thing is, is changing it....whether you are 3k or a 7k like me, you must change it. I am NOT a fan is devices for sucking it out and never will be. I still do it the old way, and I like it draining for awhile. I am never in a hurry to refill it until I see nothing coming out. You never get it all, but you will get more the old way. I see guys making statements it only takes 8 qts... yes it does if you don't get the half qt out. Put 8 qts of clean oil in a bucket then pour a half qt of used oil in there and see what you have. My cars take 8 1/2 qts everytime. Never a high oil level. I don't think I have a different motor...lol... Each to their own, and that is the way it is with oil.... I had 4 motors in the Camaro big block, each time they were torn down, they were spotless with Mobil 1. I had friends running motors with the other brands, and their motors weren't as clean. journals cruded up, valves covers coated, and crap in the pan... not with the synthetic...