I run Amsoil and change it once a year. Per Amsoil, if you are running the oil and filter they warranty it for 12,000 miles. If just the oil they still warranty the oil for 12,000 miles, but recommend changing the non Amsoil filter every 6,000 miles or 6 months.

Tom

Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety. Benjamin Franklin, US author, diplomat, inventor, physicist, politician, & printer (1706 - 1790)