91 octane?!

@Scarlet_Knight:

Because it's used it's actually less out of pocket than my previous car grand total. So I AM saving some money there.
I'm glad to hear it. I hope you got a good interest rate.

@A101:

If your [sic] living in relatively flat lands and just commute, then use the cheapest gas you can get. However, if you live in hill country, or you are hauling a lot of poeple and things all the time, then you will need to use the higer Octane as reccomended [sic].
I don't care if you live in the flattest state in the US (Kansas), you can easily put enough load on your engine to cause damage if the fuel octane is too low. Using less than the manufacturer requires is never a good idea.

you could do that, but it just doesn’t seem worth it to me. if the options are 89 and 93, just put the 93 in, but if it is 89 and 96 (where DID you find 96 ocatane pump gas anyway?), the 89 is honestly probably fine, if you are that concerned. my car requires 89, but i put 87 in it because i, like you, am cheap, and it still runs fine and the fuel economy is not noticeably impacted.

Engine damage caused by insufficient octane is so rare it’s not worth worrying about…The difference between 87 and 91 octane borders on being insignificant…Those four octane points are not going to pose a life or death issue for a modern smog engine…if you notice knock or ping, switch to a higher octane number. If you don’t notice any engine complaints, no damage is being done no matter what grade of fuel the owners manual recommends…

Most of these “premium fuel only” cars, when they trickle down to their third and forth owners, are fed regular grade gasoline and they shoulder on with no complaints or holes punched in their pistons…

@A101 : What kind of F-150 did Ford make in 1987 that required high octane fuel? The only way I can think of this being so is if the engine were modified with high compression pistons, hot cam, etc, but definitely not in stock form. If they made a performance version of the F-150 with a high compression engine in 1987, I will stand corrected.

Mountainbike,
I agree that knocking is a various term. Ping has a different noise but that does not mean for a particular car that it is a different issue. But given the large number of pings and knocks and the lower number of dead engines I’ll put as a bet a large plate of tasty mac and three cheese on the idea that it is not a clear diagnosis to a blown engine. What do you say?