Thought some of you might be able to use this info.
Last month I bought a 2011 Ford Ranger with the 4.0 V-6 and automatic. For members outside the US, this was a compact pickup that was widely sold in the Americas, but had nothing in common with the Ranger sold overseas. Except for a few 2012s built for fleet buyers at the end, 2011 was the final year for the US Ranger until the "overseas" version was built and sold here starting in 2019.
Mine had 101,000 miles (over 160,000 km), and Ford for this year gave 105,000 miles for the first spark plug change. Ford also spec'd nickel-core plugs, Motorcraft SP-412 (AGSF24N), while Rangers with the V-6 had specified platinum plugs in prior model years. And regular plug changes.
Changing these plugs and wires was a priority, especially since I've had bad experiences with plugs kept in engines too long. Nickel-core units used to be good for only 15,000–20,000 miles anyway, so 105K? A mechanic buddy got the old ones out after I couldn't budge one that was really hard to get to. He installed new plugs and wires. I provided Motorcraft wires and Denso platinum-iridium plugs that I gapped to Ford specs. He saved the old stuff for me.
Here's the surprise! He confirmed the Motorcraft plugs he pulled out were the originals because of a mark Ford used at the factory. These were SP-412 plugs, but they were still in very good shape after 101,000 miles. No cylinder had any sign of a problem. The center electrode was not as seriously eroded as I had expected. The gap spec was 0.052–0.054", and all six plugs had eroded to around 0.070" (+ or – about 0.003"). Except for being well off spec, they probably would have been good for a little while longer.
Factory-spec'd nickel plugs have really improved over the years. Based on this, I wouldn't hesitate to use that type now. But the truck runs really nicely on the new Densos.
Last month I bought a 2011 Ford Ranger with the 4.0 V-6 and automatic. For members outside the US, this was a compact pickup that was widely sold in the Americas, but had nothing in common with the Ranger sold overseas. Except for a few 2012s built for fleet buyers at the end, 2011 was the final year for the US Ranger until the "overseas" version was built and sold here starting in 2019.
Mine had 101,000 miles (over 160,000 km), and Ford for this year gave 105,000 miles for the first spark plug change. Ford also spec'd nickel-core plugs, Motorcraft SP-412 (AGSF24N), while Rangers with the V-6 had specified platinum plugs in prior model years. And regular plug changes.
Changing these plugs and wires was a priority, especially since I've had bad experiences with plugs kept in engines too long. Nickel-core units used to be good for only 15,000–20,000 miles anyway, so 105K? A mechanic buddy got the old ones out after I couldn't budge one that was really hard to get to. He installed new plugs and wires. I provided Motorcraft wires and Denso platinum-iridium plugs that I gapped to Ford specs. He saved the old stuff for me.
Here's the surprise! He confirmed the Motorcraft plugs he pulled out were the originals because of a mark Ford used at the factory. These were SP-412 plugs, but they were still in very good shape after 101,000 miles. No cylinder had any sign of a problem. The center electrode was not as seriously eroded as I had expected. The gap spec was 0.052–0.054", and all six plugs had eroded to around 0.070" (+ or – about 0.003"). Except for being well off spec, they probably would have been good for a little while longer.
Factory-spec'd nickel plugs have really improved over the years. Based on this, I wouldn't hesitate to use that type now. But the truck runs really nicely on the new Densos.