After installing an Amsoil Bypass Filter on my Prius after initial 5k miles, I changed Toyota brand oil filter at 5,000 miles but only Amsoil bypass filter at 10,000 miles. http://priuschat.com/forums/gen-ii-prius-modifications/23222-bypass-filter-install-4.html#post949400 All oil changes to date using Toyota brand oil and filters, where applicable. Will evaluate using synthetics oil in the future. Here are the pictures of the removed paper elements. Toyota filter element measured 55 inches. Amsoil filter element measured 72+57=129 inches. Comparing the two filter elements side by side, the standard filter appears to still be usable beyond 5k miles when used in combination with the Amsoil bypass filter. The bypass filter could possibly be used up to 15k miles. I have not submitted the oil for analysis to determine if the oil could be used for extended mileage beyond 5k miles. Perhaps both filters and synthetic oils could be used for extended mileage intervals. (I used a coping saw with a new blade to remove the Amsoil filter media and prevent metal contamination.) I may also add an oil pressure and oil temperature gauges in the future. I don't think these measurements are available using Scanguage, unless someone can provide some details...
