If these oils were all at the same price point,which one would you choose and why? Base your choice on personal preference,experience with use (smoother/quieter,etc),specs on paper,and additives/base stock quality. I`m wanting an SM or earlier,if possible. Nothing that`s been "watered down (removal of zddp,etc)". Royal Purple HPS or old formula Royal Purple (SJ rated) Synpower VR1 synthetic (I noticed this one is SL) Mobil 1 15W50 (is the new SN rated one as good at the old SM?) I chose these because they are all over the counter oils.