Originally Posted By: HTSS_TR
Amsoil AZO is not an extended drain oil, but after 14k miles it still has almost 3.0 TBN with very little wear metals. With the same driving habit Amsoil AZO can be extended to 17-18k miles in this engine without worrying.
It is part of their signature series line-up, their longest drain products, designed to be used to up to 25,000 miles.