I've been in the lubricants business since 1979. I've sold and used just about every brand available. After my years of research, I'm now convinced that AMSOIL is the superior product line. My 1998 Ford E-350 has right at 415,000 miles on it, changing oil every 20,000 miles and oil filters ever 10,000. The savings in oil changes alone is enough to purchase a new van, and I might add, I don't need to.