I put about 10k per year on average.
I generally change once every 2 years after initial oil analysis showed the oil was still excellent.
On an engine just switched over from mineral oil, I'll change the filter at a 1 year interval & top up with a quart.
On an engine thats had a couple changes already, I just change oil/filter every 2 years.
Oil analysis has shown that the Amsoil is good to go for a couple years as long as a quality filter is used.
The Amsoil filters have Donaldson synthetic media inside, I generally just use the cheaper Donaldson branded synthetic media oil filters that are identical.
