Many doing extended drains do use lab testing to see when to change it.
I myself am going by the 7500 mile changes, using Rotella T synthetic blend in use member and full synthetic in winter. I plan on adding an Amsoil bypass filter soon as well.
I myself am going by the 7500 mile changes, using Rotella T synthetic blend in use member and full synthetic in winter. I plan on adding an Amsoil bypass filter soon as well.