Mobil-1, Amsoil, Redline, Royal Purple, each brand has its fans. And they all claim you can go a year or 12,000 miles, etc. between changes. I wonder if there are any comparison studies to show which is really best. Or are they all equally good?
Also, does anyone know of an oil filter that will last that long? I know Amsoil has a spin on bypass filter as well as a high tech full-flow filter. I guess I am just old-school. Although I use synthetics (Royal Purple now) I still change it at the regular intervals.