I have a 1997 Ford F250 7.3 PowerStroke and it's strictly used as a work truck for towing and hauling whenever I need it, rest of the time it's parked. Needless to say, it doesn't rack up miles fast. Last August, I changed the oil from conventional 15W-40 to synthetic 5W-40 and installed a orange Fram PH3786 filter. Coming up on the year anniversary in a few weeks and just barely over 2k miles on the change, oil is still relatively clean on the stick. I'm assuming this combination can easily do 5k miles, being synthetic and a quality filter. Should I change it or run it another year and then change? If there's no need to spend the money I'll save it for something else the truck needs like a coolant flush before winter! Oil used was Rotella T6 if that means anything. Thanks in advance!
2004 Toyota Tacoma 3.4 V6: Mobil 1 AFE 0W-30, FRAM TG-3600 filter
1996 Ford Contour 2.5 V6 QSGB 5W-30, MC FL-500S filter