Stick with Motorcraft, or if you on a budget, go with Autolite. Other plugs just don't seem to last as long in Ford Engines. one of mt dads old engine builders told me what he does.
ford, Motorcraft, or Autolite
chevy, AC Delco
mopar, Champion.
Ford didn't use dual platinums off the assembly line, and still recommends a 100K change interval.Your ignition system NEEDS as a minimum DUAL platinums (waste spark).
Why not spend a little more and go with Autolite Iridium? Or NGK Laser Iridium? They perform better than dual patinums, they put less electrical strain on the coils and wires, burn more efficiently the fuel in high-load moments, last longer...
Both companies have on-line selectors that can help you choose the right spark plug.
...in a waste spark ignition, both the center firing electrode and ground
electrode will see gap erosion. In plugs with a positive polarity, most wear will occur at the center-firing
electrode. Plugs with negative polarity will experience more wear at the ground electrode. As a result of
this, vehicles equipped with waste spark ignitions often use double precious metal spark plugs, such as
the Laser Iridium or Laser Platinum. These dual precious metal plugs feature either iridium or platinum
on the center firing electrode and platinum at the ground electrode. Because these electrode materials
are denser, gap erosion is reduced, allowing a longer service interval Being that these materials are
denser, this will reduce gap erosion, thus leading to a much longer service interval. The use of nickelalloy or single precious metal spark plugs in vehicles equipped with waste spark ignitions will result in
more aggressive gap erosion and shorter spark plug life.
I told you that Motorcraft are not wonder-plug. They resell plugs made by others (Autolite).My old NGK TR55 is installed now, the engine misfires under load, I was hoping new sp486 would solve that, but they did the opposite.