OK-- I asked the question on the "dumped my castrol" thread. It's my contention that most of this "car runs better since I changed my oil" business is simply placebo effect pure and simple. A 1-2% change because of weight change or going from dino to synthetic simply isn't enough to feel in the seat of your pants. Same with improvements after oil changes. Agree or (I'm sure most of you will) disagree. Let me have it.