Run the oil 7,500 mi. and get an oil test. That is the true answer. I have run my Amsoil for 46,000 miles with an oil filter change every 15,000. The oil was still good at 46,000 mi. but the numbers were getting a bit high. I went with Amsoil again and went 39,000 mi. and by then the test said it was 80% of the maximum allowed for oxidation so I changed it. You can so easily go 10,000 miles. My GMC diesel computer is like clock work, every 10,000 miles. Now I use Shell Rotella T6 and change every 15,000 or so but use a mobil 1 oil filter. Keep your air filter clean and you wont ever have a problem unless you are in dusty roads.
Ding ding ding. If it works for multi-million dollar machinery and Jet engines, I bet it will work for an extremely complicated combustion engine.
Look up Blackstone Labs
