I’ve used synthetic (Mainly Mobil-1) oil since the 1980s. Never saw a MPG increase (And I keep detailed logs). I mainly use it for the added protection. I like to keep my vehicles for a long time. So I’m wondering if others have experienced the zero mpg increase with synthetic vs. conventional oils. Also, what oils do you use? Castrol has Syntec and Edge. Is Edge worth the added cost?