For those about to "knock"......

[hampsterzone]

Excellent answers my friends! I truly do appreciate the "honest" feedback! In addition to your explanation of octane ratings, what would you recommend I run in my truck? 87 octane is definitely cheaper by far around here lately. With that being said, what should I do with my custom tunes? Change them over to 87 because there is not much difference or keep the 91 custom tunes because they are superior and worth the extra money to run the higher octane? And lastely, how much would it cost me to have the tunes changed over to 87 octane on both tunes if in fact you feel I should switch? Thanks in advance, you are awesome!!!!!!

[Jackpine]

I'm going to add one observation about your tech's telling you that the high-priced juice caused the plug failures. It DIDN'T! The problem is most likely a result of the non-Motorcraft plugs having just a tad different heat dissipation capability. This will either cause them to run hot (which burns the electrodes) or cold (which tends to cause fouling).

There's really not just a whole lot else that can go wrong with a plug. It's not exactly rocket science.

And, yes, your truck WAS designed to burn 87 octane gas. I personally think using 91 or 93 is overkill, but it won't hurt anything. You SHOULD get somewhat more power out of 91 octane, since Bill has adjusted the fueling and timing for it, but he can't adjust the compression, which is what the high-priced stuff is really designed for (a higher compression ratio).

If you had a blower, you'd want to use premium.

There's nothing else in "premium" gas that helps or hurts an engine except the slower burn and resistance to detonation. Premium is actually harder to ignite!

- Jack