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Since it’s normally aspirated, you’ll PROBABLY be fine. But don’t pump and pray – test it. Log some hard pulls, look for knock and watch for the ECU pulling timing, especially at high revs.
If you don’t have OBD logging yet, the OBDLink MX and the TorquePro app are a powerful and affordable combination.91 or higher is recommended by Honda due to the design (higher compression) of the engine. Using fuel below 91 will cause excessive carbon build-up and detonation (pinging) which could lead to valve problems, clogged IAC or EGR passages, stuck IAC or EGR valves, fouled spark plugs, dirtier oil, etc. A tankful or two of 89 or even 87 won’t hurt, but not long-term. Honda designed the vehicle to run on 91+, so it should be given 91+. It’s more expensive fuel, but it is what the engine requires.
OK, different question there are cars that use regular gas (87)
and the premium cars use (91+)
what is the 89 octane fuel good for ?Mid grade is specified for some cars. All cars that specify regular *can* use mid grade and premium, although it’s a waste of money for engines with lower compression that are designed for 87 regular. Engines spec’d for premium should only use premium for the reasons I mentioned above. The octane number represents the percentage of octane. Regular “87” gasoline’s fuel fraction contains 87% octane, 13% heptane. The octane acts as a fuel stabilizer and causes the fuel to burn a little slower. The rest of gasoline’s components are additives and detergents. The higher the octane number, the slower the burn. Lower compression engines need less octane because they want the fuel to nearly combust from compression alone. The lower the octane number, the less compression required to combust the fuel. The spark plug is there to ensure a good flash point and to make sure the fuel combusts on time and as completely as possible. Higher compression engines will ignite the lower octane fuel sooner, possibly before the spark plug fires (which is called predetonation, or usually shortened to just detonation) and is responsible for the pinging sound since the piston isn’t fully ready to travel downward when the cylinder combusts. This is also what is responsible for the excessive carbon build-up I mentioned since the combustion is only partial to what it normally would be. The more incomplete the combustion, the more carbon is left behind. This is why higher compression engines need higher octane fuel, so that the combustion is a little slower and little more complete and won’t predetonate, thus less carbon residue and more stable ignition timing. This explains why using 89 or 91 on an engine made for regular isn’t very good idea either, because the lower compression engine needs a faster burn, not a slower one, so fuel economy will actually decrease, as will output power. I hope this explanation helps to debunk the myth that higher octane numbers are “better.” There are a lot of fuels that will burn in your engine. Charcoal lighter fluid, camp stove fuel, even kerosene or hard spirits like Everclear can fire an engine. However, price notwithstanding, just because they will run the engine doesn’t mean that they are suitable substitutes for the correct grade of gasoline. I ran my Jeep for a day on camp stove fuel once, in Florida after a hurricane. The electricity was down, so the gas pumps didn’t work, but the hardware store had camp stove fuel. I put five gallons in the tank and went about my business. This was an emergency situation though. Not recommended otherwise. I miss that tough old Jeep.
[quote=”AcuraTL3.2″ post=187687]Do to extreme price difference, What happens if you use 89 octane in 06 Acura RL ?[/quote]
Use the fuel recommended by the manufacturer. The recommendations are there for very good reasons.
To be honest, if the price of fuel is an issue, you’re driving the wrong car for you.
The next time you’re shopping for a daily driver, pay attention to things like the recommended fuel, and the cost of replacing the recommended tires. (Larger diameter and/or low profile tire sizes, which may be used on a vehicle to enhance a vehicle’s perceived performance cachet or simply for looks, are more expensive to replace than mundane “grocery getter” passenger car tires.) Quite often, the car that best suits your needs is a lot less sexier than much of the eye candy that’s out there.
Where I live 91 is the lowest rated , followed by 95 then 98 being the highest , I run both cars on 98 PULP
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That isn’t surprising. Most of the non-North American world uses a scale called “research octane number” or RON that determines the big number posted at the pump. However, a close look at the sticker should reveal a second number there called the “motor octane number” or MON, that indicates a different measurement of octane in the fuel for that grade. In the US and Canada, the number on the sticker at the pump is based on a different scale called “anti-knock index” or AKI, which uses an average of RON and MON (R+M/2) to represent a more accurate ratio rather than listing the two RON and MON numbers on the sticker. So, in North America the numbers on the pump will be 4-6 points lower than elsewhere, but, at least in theory, are designed to reflect a more accurate fuel component ratio. This is why in the US and Canada it is claimed that an 87 rating = 87% octane, because the number was intended to mean that. Thus, in your area, 91 RON, with around 83 or 84 MON yields approximately 87% octane. As a caution, based on the information I posted previously, if you’re running 98 PULP (PULP = “premium unleaded petrol” for the North Americans unfamiliar with the term) and your engine has a somewhat “normal” compression ratio of 9:1 or less than you should be using a lower grade, even 91 RON, else you’re wasting money, losing power, and building up carbon deposits. The bottom line, always use the fuel grade recommended by the manufacturer.
[quote=”relative4″ post=187689]Since it’s normally aspirated, you’ll PROBABLY be fine. But don’t pump and pray – test it. Log some hard pulls, look for knock and watch for the ECU pulling timing, especially at high revs.
If you don’t have OBD logging yet, the OBDLink MX and the TorquePro app are a powerful and affordable combination.[/quote]A modern NA engine will just adjust timing so the engine can operate safely. The same thing that happens if you put premium in a car that only requires regular. The computer just adjusts a few things and carries on.
Some cars will plain start to run like shit on lower octane fuel. Maybe not to the point of actually causing issues, but it can be noticeable.
Personally I drive a factory high output turbo engine. Even running lesser quality premium fuels will make it run like shit.
Honestly, for the few dollars difference a tank, there’s no reason not to run premium if your car requires it.
[quote=”DaFirnz” post=187845][
A modern NA engine will just adjust timing so the engine can operate safely. The same thing that happens if you put premium in a car that only requires regular. The computer just adjusts a few things and carries on.
[/quote]That’s not quite true. What really happens is that if the octane is too low and causes detonation, the knock sensors detect this and will retard the timing to cancel the knock. This will cause a loss of power. Running higher octane fuel in a lower compression engine will not cause detonation, so the computer will do nothing to the timing. But since that fuel doesn’t completely burn due to the longer burn time caused by the higher octane, this will also cause a power loss.
Some cars will plain start to run like shit on lower octane fuel. Maybe not to the point of actually causing issues, but it can be noticeable.
Inferior fuel can also cause knocking/pinging, and this will result in retarded timing and power loss, to point of stumbling and hesitation depending on how poor the fuel quality is. Also, some people have cars that need mid-grade or premium and they don’t realize it. The required fuel should be noted in the owner’s manual, and usually also on the door pillar decal (the one with the vehicle weight and tire pressure).
Honestly, for the few dollars difference a tank, there’s no reason not to run premium if your car requires it.
I completely agree with this. Always run the engine on the required fuel. No matter the price. You can survive on a pure junk food diet, too, but you won’t be healthy. You have to feed yourself the fuel your body requires, as also you have to feed your vehicle the fuel your engine requires.
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