Using Regular Unleaded Fuel

[MrPeabody]

What are the short or long term negative results(if any) of using regular instead of super unleaded fuel in a NSX? This is a confusing issue for me because the owners manual on my other vehicle(X5)states premium, but the dealer recommends regular unleaded.....

 

[socalx]

I don't think you will get an answer, bc i don't know a single owner that runs regular. The premium fuel is recommended due to the setup of the engine. (timing, aluminum materials with no liners, high redline and variable valve timing). This is recommended for a reason.

also if i had a bmw X5 and the manuafacturer recomended premium, that is what i would run. While it is true that there is no benefit for running more octane then needed, i wouldn't run less octane then specified.

 

[Hugh]

While it is true that there is no benefit for running more octane then needed, i wouldn't run less octane then specified.

Not only is there no benefit, but running premium gas in a car designed for regular will actually produce less octane.

Contrary to popular belief the only thing that octane does is retard detonation. Therefore in a car designed for regular, you won't get complete combustion with premium gas resulting in a loss of horsepower coupled with a loss of money for paying for the unnecessary premium gas.

That being said, the NSX is designed for premium gas due to the high compression ratio. Using regular gas will result in early combustion, manifested by pinging which could eventually damage your engine.

 

[s14_tat]

What are the short or long term negative results(if any) of using regular instead of super unleaded fuel in a NSX? This is a confusing issue for me because the owners manual on my other vehicle(X5)states premium, but the dealer recommends regular unleaded.....

you will run the risk of detonating and causing engine damage by running 87 octane. The C30 or the C32 engines in the nsx have a compression ratio of over 10:1. What the octane rating basically means is the fuels resistance to pre igniting. What pre ignition is, is when the combustion happens too soon before top dead center of the compression stroke on the engine. This causes a shock wave or very powerful that is trying to force the piston down when the piston is trying to move up to the top of its travel.

This is why you will sometimes hear a rattling sound coming from peoples engine under a load, it sounds kinda like a broken ball bearing when this is happening. There is some kind of fail safe to prevent this, the engine has a sensor called a knock sensor, when this sensor picks up a frequency that is not considered to be normal, the engine will retard its ignition timing up to the max it is allowed to try to stop the engine from pre igniting. This will then effect your horsepower and fuel economy for the worse. The stock ECU on vehicles are smart enough to learn its engine parameters based on long term driver input. So if the engine see's crap gas or a very light footed driver for most of its life, the engine will perform like so. If you have a driver who is always reving it, and redlining the engine, the engine will always be used to making its max power and will produce more power or the power that its suppose to make.

Also another disadvantage of 87 octane fuel is that its not as clean so it will gum up your valves and clog your fuel injectors, while the 93 octane have detergents in it to keep your engine clean on the inside. The price difference more than makes up for it. Plus you don't run the risk of causing permanent damage to your engine, or have less power or have crappy fuel economy.

If your dealer is recommending that you run regular, I would not trust a word coming from there techs because obviously know very little about basic mechanics.

 

[Hugh]

Also another disadvantage of 87 octane fuel is that its not as clean so it will gum up your valves and clog your fuel injectors, while the 93 octane have detergents in it to keep your engine clean on the inside. The price difference more than makes up for it. Plus you don't run the risk of causing permanent damage to your engine, or have less power or have crappy fuel economy.

That's a myth and the reason a lot of people use premium fuel in cars designed for regular. Premium fuel in a car designed for regular means LESS power due to incomplete combustion.

"Top Tier" gasolines (Google it) such as Chevron and Shell have the same detergents in all their grades. The only difference is the octane.

 

[MrPeabody]

Thanks for the replies, they all made perfect horse sense(no pun intended):biggrin:
I actually have not purchased a NSX yet, and am still looking. For simplicity, I have pretty much narrowed my focus down to the 03-05 years. The initial price on a NSX that new certainly is one big hammer. But I figure you pay one way or another, and the fuel issue was something that I wanted to be clear on.

 

[Hugh]

This is a confusing issue for me because the owners manual on my other vehicle(X5)states premium, but the dealer recommends regular unleaded.....

Tell your dealer I say he is a clueless idiot and if he wants to debate me on this, he's welcome to log in and post in this thread.

 

[MartinSD]

Greetings

If you are looking for a G2, don't forget to look at the 2002 model year machines.

Martin

 

[tosugrad]

Your BMW dealership are idiots.

 

[NSXFRIEND]

It could cause catastrophic failures to the emission regulator devices and Mas air flow sensors. With the Gasoline already using 10% alcohol/ethanol it would be in the best interst of Nsx owners to use only premium unleaded gasoline. I have only used premium in all my cars, daily drive beaters included and have never in 17 years of driving experienced fuel injector or O2 sensor runability issue related problems.

In a free market society, you always get what you pay for with few exceptions.

Per service manual unleaded premium 91 octane 96 Ron is recommended.

 

[NSXAMG996TT]

The stealership needs these reliable cars to break down to support their service department. It's called job security.

 

[jond]

What are the short or long term negative results(if any) of using regular instead of super unleaded fuel in a NSX? This is a confusing issue for me because the owners manual on my other vehicle(X5)states premium, but the dealer recommends regular unleaded.....

Simple. It will cause your cylinder walls to develop cracks over time and cause your engine to need a rebuild.
You realize a new NSX engine cost $30,000.
Why would you even consider it not treating it right?

 

[NSXFRIEND]

Simple. It will cause your cylinder walls to develop cracks over time and cause your engine to need a rebuild.
You realize a new NSX engine cost $30,000.
Why would you even consider it not treating it right?

Hmm a Diablo Motor cost's $25k to rebuild lol

 

[peiserg]

Simple. It will cause your cylinder walls to develop cracks over time and cause your engine to need a rebuild.
You realize a new NSX engine cost $30,000.
Why would you even consider it not treating it right?

I've always wondered. WHy do people throw out the $30,000 for the motor arguement. Who here has EVER paid that much, or even close to it? $10-12k is more realistic (though still..not cheap!)

Even the guy who had jiffy lube pay for his motor opted for Comptech to rebuild it with all new race parts for far less than $30k.

Pet peeve I guess. Kinda like the "PM Sent" message people put in the forum. Who cares? I should preface all my replies with "reply sent."