Besides the point of the post but I would recommend an oil analysis. A good tribologist will give you the right interval to change, viscosity, status of wear to your motor etc. They will review friction, wear, lubrication and advise the best motor oil to go for which could affect cost hopefully in a good way and not in a bad way. Check out Newtonian and non-Newtonian fluids with respect to motor oils. With your best interest in mind, if you're planning on buying another barrel, I would advise this approach before dropping cash.