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20
votes
8answers
30k views

Will higher octane fuel improve gas mileage?

I've heard from some people that high octane fuel will increase gas mileage. Around here, we have the basic unleaded(87), mid-grade(89), and premium(93 or 91). I've been using the basic 87 unleaded ...
13
votes
3answers
3k views

Static vs. Effective compression: Why does higher effective compression not require higher octane gas?

Background I've been trying to do a lot of research on boost lately because I'm planning on running a moderate turbo setup on my daily/light-duty-autox car in the future. I'm trying to get into the ...
5
votes
1answer
2k views

Difference between high octane and low octane?

What is the difference between high octane and low octane fuel? I'm not asking if one is better than the other for my vehicle, specifically, but rather what occurs differently both scientifically and ...
4
votes
8answers
6k views

When given a choice between octane 89 and 93, which should I choose?

I just recently got a 2005 Volvo S40 with a turbo engine; I want to take good care of it, so naturally, when the instruction manual recommends 91 octane fuel but says it takes a minimum of 87, I have ...
4
votes
2answers
326 views

Switching to a higher octane

This may be a very noob question to ask. But I recently got this car and was used with 92 octane petrol. However, to my negligence I overlooked the user manual which states to include 95 octane ...
4
votes
2answers
4k views

Can I use lower octane fuel at high elevation?

Here in Colorado, gas stations sell "regular" gasoline which is rated at 85 octane ((M+R)/2). In most of the rest of the US, 87 octane is the lowest grade available. (As noted previously, higher ...
3
votes
3answers
639 views

Is it feasible to Turbo a NA engine while maintaining 87 AKI octane fuel use?

I initially thought there should be a way to bolt on a small aftermarket turbo onto my naturally-aspirated Honda D17A2 (9.9:1 compression ratio) engine in my EM2 Civic EX without having to switch from ...
2
votes
2answers
81 views

Toyota Sprinter does not specify octane rating

I have recently acquired a 1999 Toyota Sprinter (Japanese domestic import). I realised that the engine "ping" so someone recommend to use 90 Octane petrol. I went through the manual but it only says ...
0
votes
1answer
128 views

How much Octane Fuel does Honda CBR 250R (India Version) needs? 91 or 93?

Honda CBR250R STD 2013 Model's manual state that fuel(petrol) used should be 91 or more. Seems like they have defined the minimum threshold of RON than stating the optimum RON for the given bike. ...
0
votes
0answers
22 views

Will premium gas give me extra benefit? [duplicate]

My car: Toyota Camry 1994 LE, 4 cyl, 4 door sedan, automatic 127000 miles. Will buying Shell premium gas give me extra benifit?