I own a 2013 F150 FX2, 5.0 liter with about 51K miles. The owners manual says to change the spark plugs at 100K, but I'm considering replacing them now. I'm not experiencing any issues, but I plan on keeping the truck for several more years and want to keep it in good operating condition. Any advice on what to do? I have no plans on a performance upgrade, just basically want the truck to run like it did when I drove it off the lot. Any thoughts you guys have would be greatly appreciated...thanks!

 

If you feel it is necessary I would pull out one plug and check the gap. However at that mileage I would leave it alone if it is running great and there is not an observed drop off in fuel economy or performance. Changing plugs on the naturally aspirated engines is not as crucial as the EcoBoost. I would probably wait until 80k and if you decide to change them I recommend using Motorcraft plugs as that is what they are tested and designed around.

If anything I would change the coolant early around 65k - 70k before it starts to breakdown in the cooling system. Prevent most of the coolant slime and gunk. It is important to maintain coolant pH between 8.5 and 11. If a coolant's pH drops below 8.5, chances are it will become aggressive with ferrous metals such as aluminum, copper, brass and cast iron and steel. When levels above 11 are reached it becomes aggressive to aluminum and solder within the cooling system.

 

if the motor is running fine and there is no issues concerning fuel economy or misses then spark plugs can wait. if you still want to change them that's great