"I have only ever put premium fuel into it since acquiring it two years ago, and yes it sat idle for three years prior to my ownership."
From everything I have ever read on the subject premium grades of gasoline only yield a benefit if the engine actually requires the higher anti-knock properties due to a high compression ratio, supercharging, turbocharging, excessive combustion chamber deposits that retain heat or actually glow, overly advanced initial timing, overly agressive centrifugal advance curve, etc.
Otherwise, all the articles explain, the extra expense is wasted. I've been interested in this subject for a long time and it seems that when car enthusiast magazines and Consumer Reports say exactly the same thing over and over there's probably something to it.
Either we have the same interests in cars or one of us is stalking the other....(just kidding, of course)
Here is my take on the fuel/gasoline sold in the US vs(Western-) Europe:
I have been to Europe and driving there, on and off for the last 30 years, it seems odd to me that in the times before Unleaded fuel (US around 1975, Europe not until the late 1980ies) you could get 99 octane fuel, while in the US some places were boasting with 92 octane (whoohoo, Union76) as premium.
US were the first to get rid of the lead, BUT again, when Europe follows their footsteps, the same numbers for octane ! They are one step up.
I know the fuel is twice as much there, but that is because 60 to 80% of it is taxes over there.
Why is it, that one cannot get/the market does not supply 99 octane gas ?
Now as to both our answers in this thread:
I was giving the short version about getting 'premium gas' here in the US.
What I really should have said, is that any gas here does not make a difference, I am afraid for the car Eric is driving.
If it only has 118k miles, it probably has most of it's HIGH compression and that is why it is just puttering on that gas he is buying, regardless if regular (86 octane) or "Premium" (92 Octane)
Thoughts anyone ?
I would really like to know