Originally Posted By: gathermewool
Originally Posted By: SteveSRT8
But back on topic, most folks do not even understand octane. Slower burning/harder to ignite fuel is not always the best fuel. I used to retune vehicles a lot in the 80's to run well on regular, and many times a bit of fuel enrichment was all they needed. Most times we ADDED timing.
Talking about tuning across differing platforms can confuse folks, as even the same cars can require slightly different tweaks to run sharp.
Absolutely, but we're not talking about tuning here. We're talking about stock blocks that either recommend or require higher octane fuel.
While tuning, both fueling and timing (and valve control and wastegate duty cycle, and etc) need to be adjusted. The first thing most do in turbo Subie tunes is mess with the fueling - stock likes to keep AFR near or just less than stoich even after the onset of boost. Aftermarket or pro-tunes dump it down to ~11-12 quickly and keep it there. Tip-in enrichment is important, too, to combat exactly what the OP seems to be experiencing. Add a little more fuel and maybe take away some timing and no more pinging.
Outside of tuning for fuel, a fuel suited to your stock requirements, even if only recommended, is what should (not shall) be done (I.e., running 93 octane in an engine that recommends 91 octane is a waste of money if 91 is recommended; however, 93 is just fine if 91 is required, and the stock tune is known to be aggressive - my STI, for example.)
In the end, use what's required or recommended. You're doing yourself ZERO favors by using a lower-than-recommended octane. Unless you've got an old iron block, like the OP, or a motor known for taking abuse and low octane without spinning a bearing or damaging pistons, then run the required octane. Even if you drive gently and mostly highway, where the higher octane may provide no benefit, the first time you get on it, which we all do, damage may occur. It's as simple as that.
^ This. Everything else is falsehoods