On oil and filter schedule, I use 5w-40 full synthetic like Dave suggested and change every 5000 miles. Fuel filters are done every other oil change (10,000 miles). Motorcraft on all filters, I was using Delo 5w-40 synthetic but they changed the oil rating so I went to Rotella T6 5w-40 with no issues. I believe Dave has been using T6 for a long time with no problems. Regardless of what is causing the surging this is the best maintenance plan to take are of that motor. I also added a Fumoto drain valve and oil changes couldn't get any easier. Consider the brass replacement drain plug for the frame mounted fuel filter housing/pump. Easier to drain the water separator.