I'd hate to see this thread die. While it has covered fuel octane pretty well...and even tried it's hand at towing capacity and limitations of the Raptor drivetrain and suspension...this slid by un-noticed in robbcwz's post:
The Raptor supplement shows spark plugs are SP534. Those of us who have pulled our plugs know that is not true from the factory. Factory plugs are SP550.
Will your truck run with SP534's? Of course. But is that what Ford puts in the truck NO. Will it run better with SP550's? YES. And that is precisely why Ford switched to them.
Let that be a lesson to all the penny pinching, manual quoting idiots running 87 octane.
And now, let the thread continue...the year is not over yet!
PS - have you looked up what the prefix DF stands for on Urban Dictionary?
My posting of the manual excerpt was in relationship to the previous comments of "only 91 OCT" when the manual was actually saying the you could go as low as the 87 and so you have taken my post somewhat out of context by using it for spark plug arguments and rather strange comments such as "Let that be a lesson to all the penny pinching, manual quoting idiots running 87 octane" which has no explanation or reference in your rambling post.
Truth is that for most, if not all parts, one should use the vehicle VIN# so that the parts tech (in theory) will look up and be referenced to the latest part. If you walk in and ask for "SP534's" there is a good chance you'll get them as opposed to giving the VIN and getting the latest SP550's.
When it becomes time to change my plugs I will go the VIN# route and not "I need SP550's gapped at .028 because FRF says so". There is some intelligence in here but also a lot of scary idiots working without skill on a $70k vehicle. I wouldn't trust half the people with the kind of changes being made when most demonstrate zero ability to even change their oil successfully. One needs to be very careful in whom they trust, I believe.
So back to the evils of 87! I've ran 87 almost exclusively for my Gen 2's 15,000 miles. To this point, the majority of its time is spent doing trips of 100 to 300 miles; very little in town traffic or red light racing, and it seems to do fine on 87 and, on the occasions a little tete-to-tete racing has been needed it has never failed to perform. Did I miss the extra 10HP from 91? I don't think so. Did I miss the 0.1second from the red light - not yet!
If my only mission was to treat every trip as a full speed, race from every light regardless of whether there was anyone to race and all at full boost, then yup I would be using the higher octane.
My truck gets used a lot in a number of driving styles with the only missing mode so far being the BAJA since the high speed desert racing is hard to find in Louisiana! It gets driven hard but not abused. But I'm feeling confident that when I change the plugs at 30k I will not be sitting there wishing I'd have run the higher octane.
And to conclude, I have neither the Sasquatch drilled hole in the intercooler, and nor do I have a catch can -and so by that I may never make the 30k mark, yes?