- Registrado
- 5 de Abr, 2025
Octane is a contentious issue. Some cars can get "better-enough to justify" mileage on higher octane fuels, others can't. Since you said "two years", I'm assuming this is a more modern/(post-recession at least?) car.
Essentially/as you may already know, when octane is too low, it triggers knock/harmful predetonation. Octane is a meaaure developed in the '50s, it's relative to the chemical, Octane, which was selected as the best "baseline" hydrocarbon to standardize fuel against, and the best hydrocarbon of the type to resist knock. The engine detects the low octane issue via the knock sensors (literally just tuned accelerometers/ears designed to pick up spark knock) and retards the spark timing (and valve timing if applicable) to compensate, leading to (sometimes significantly) worse power and fuel economy, as combustion is triggered in a controlled fashion later on in the stroke, and since the piston is often traveling a similar speed to the combustion event itself, the combustion has to "catch up" and wastes a ton of energy as it races to meet the already-descending piston. This also reduces the "effective" compression ratio.
Toluene is the current standard additive to increase octane, alonside ethanol. Higher octane fuels contain drastically more toluene by volume, which is why, excluding the most esoteric (and cost-prohibitive) formulas, octane additives don't really work. It's also why Premium fuel is more expensive, because Toluene isn't cheap. (However, it's almost always run at a huge margin thanks to marketing getting nogs to buy it as a "treat" for their low compression 30" rim caddy.)
Certain newer high end (German) cars actually contain sensors to adapt proactively to the octane level, similar in function to the common flex-fuel system.
The problem is that knock sensors are a reactive measure. If you run a car below its desired octane, it will repeatedly and regularly "adapt" and expose itself to (some) knock while doing this. This is especially bad for modern Aluminum engines.
I would take your spark plugs out and look for pitting. If it's at all present, (including "the carbon has some pits in it") you are slowly damaging your engine and need to at least use midgrade. If you live in a state where 93oct is usually the standard for Premium, you can go to a Sunoco and get 91oct for a bit cheaper, if you want to go that route. (People usually think the 93oct at a sunoco is somehow "enhanced", when it is in fact normal premium in many areas).
Last time I used one of these things I ended up "milling" a fucked up transmission fill plug (over the course of days, and in a bad spot so no hammering) into a perfect cone, that was the last straw and I sold that car on Facebook. Turned me off to the whole idea of extractors, but might only be worth it to buy something nicer/with more "bite" if you work with soft bolts, my extractors were amazonian chinesium.
If I recall correctly, at least on the 2g MR2, this is due to a piece of NVH foam Toyota had been placing in a bad spot, where it got exposed to salty drain/road water and behaved like an electrolytic sponge on the back of the panel. A lot of people just pull these out.
>He doesn't have his $20 per 5 purchases of $20 or more Autozone Rebate
It's really nice when you replace your duralast components monthly lel
