Good morning from the Pacific NW... I purchased a very well maintained 99 F-350 SD with a 7.3, complete with maint records. The vehicle has an Amsoil remote dual filter set up and the previous owner was using Baldwin oil filters. I subsequently replaced the filters with Amsoil EaBP100 and EaO26 filters and started running Rotella T5 15-40. I switched to the Amsoil filters to extend the filter change time, but I change the oil per Blackstone feedback. My question is this: When changing the oil, do I remove the filters, dump the old oil, replace with new and reinstall? A neighbor claimed I should just leave the old oil in the filters... doesn’t make sense to me. I appreciate your advice.