I just bought a 92 Explorer (4.0) and notice the engine has autolite 765 (Autolite Resistor Plugs) spark plugs. I've read on here that the 4.0 engine should have double platinum spark plugs, preferably from autolite/motorcraft. Here are my questions:

1. Are these the correct spark plugs to use?

Autolite APP765 or Motorcraft AGSF22PP

2. The autolite website lists the 765 as an acceptable spark plug. Will there be a difference in idle and performance between a new autolite 765 (non platinum) and a new Autolite APP765 (double platinum). Or is it only how long the spark plug will last.

Thanks for any help. I greatly appreciate it.

 

According to Motorcraft's website, the '92 engine actually came stock with copper plugs. I personally prefer to run the copper plugs for that reason. I tried a set of Splitfires once, and the engine pinged like it was going out of style. I don't know how much of that was from the platinum electrode and how much came from the V electrode, but I've decided to stick with OEM specification. From there, you enter into the debate over copper vs. platinum, which always seems indecisive to me.

 

I thought you should use Autolite double platinum plugs because the plugs in each bank get the opposite polarity spark. So what this does is erode the outer electrode on one plug, while
eroding the center electrode on the plug in the other bank. This is why having double platinum (platinum on both electrodes) is important. Anyone disagree with this? I found a lot of this info on the message board.