http://www.cartalk.com/content/premium-vs-regular-1#4

Q: My owner's manual calls for premium gas. Do I need to use it?

A: In that case, the answer isn't quite so clear. In a high-compression engine that's designed to run on premium fuel, premium will provide some additional power. But, if you want to save some money, you can probably still fill up with regular, unleaded fuel most of the time.


http://www.cartalk.com/content/premium-vs-regular-1#9

Let us show you! Here's what's going on in the cylinders inside the engine during pinging or knocking:

Illustration #1: The piston begins to move upwards during what's called the, "compression stroke," compressing a mixture of fuel and air.

Illustration #2: In a normally operating engine, the spark from the spark plug ignites the mixture of fuel and air, causing an extremely rapid burning of the fuel in the cylinder. That's good. It's what creates the pressure that makes the piston travel down very fast, causing the crankshaft, your transmission, and ultimately the wheels - to turn.

Illustration #3: However, it's possible for the mixture of gas and air to burn somewhere else in the cylinder, simply from the pressure (or compression) within the cylinder, and not from the spark. That's called "pre-ignition," and it's more likely in a high-compression engine.

Illustration #4: When the fire you want (that's the one from the spark plug), collides with the fire you don't want (that's the one resulting from the pre-ignition), the result is a ping or, if the pre-ignition fire is big enough, a knock. The degree of severity, including the amount of noise generated, is determined by how big that unwanted flame is.


Q. How does high-octane gas help?

A. Compared to regular gas, high-octane gas requires higher temperature and pressure to ignite, so it can withstand higher compression without reigniting. As such, it's less likely to result in premature ignition, and therefore prevents pinging and/or knocking.

In other words, it's a form of protection for high compression engines.


Q. So, I should use high-octane gas to prevent pinging?

A. High-octane gas will prevent pinging.

But these days most cars have something called a knock-sensor, that will - under many circumstances - obviate the need for premium gas. Just about any car that's more recent than about 1996 will have a knock sensor.

 

I disagree with others who say it's premium or nothing. I drove an 04 LX 470 for three plus years and never one time put anything other than regular gas in that SUV. I also never once had a problem mechanically, because of using "inferior" gas.

John

 

For the Genesis V8's (4.6 &.5.0) they say it's OK to run either regular or premium. I believe they show the hp and torque ratings with each type of gas in their specs.

 

It's not hard. If they recommend premium, use premium. If not, put whatever you want it it, well not diesel or E85 :P

 

And the debate continues.

As a note, I just got a new vehicle with 10.8:1 compression ratio and the mftr specifically states: "Use REGULAR gasoline."

One of my Poncho GTO's wouldn't last 6 mos on regular today. And they are only 10.25:1.

John (Enigma389) writes:
"I disagree with others who say it's premium or nothing. I drove an 04 LX 470 for three plus years and never one time put anything other than regular gas in that SUV. I also never once had a problem mechanically, because of using "inferior" gas. John"

He (John) is actually correct (and not just for himself). I have spoken to a few senior Tech Specialists @ Lexus dealerships about this. They have to be careful about what they say knowing who helps make their paychecks. But off the record, they have "hinted' that what John says makes sense.

Let's use some common sense here: All of a sudden "Lexus says use Premium gas" so why mess around burinng anything else !!!! ... and then in the same breath, almost the same people say they simply do not care what Lexus says about 5000 mile oil change intervals ..... and because they 1) don't drive their car alot, or 2) they use Mobil 1 ( - and please know......Ya really oughta check your facts here ...since Mobil 1 in the US is NOT fully synthetic... It is Blended with Dino and is actually no better than a "blended" oil) .... or 3) they simply do not care what Lexus tells us .... and so subsequently they change their oil every 10000 miles or so. What happened to following the manufacturer's recommendation ???

It's amusing that we make our own "rules" as they best serve our own purposes.

But it's no sweat off my back as I snagged a 2 lb Largemouth on my 3rd cast this afternoon.
However, and so, as I originally started ........
"The Debate Goes On (and On) ........ (and On) ........ (and on).........

Y'all play (argue) nicely now .... Mikey Lulejian - Lake Oconee, GA

 

I'm going to go ahead and sound ignorant for a second. I wonder what drivers in japan are using? I've been to Japan but don't remember a gas distinction at their gas stations. In addition, I'd like to humbly state our cars are a bit more pricy because of the importing costs.


I wonder if foreign drivers use premium gas or not?

 

Good point.

 

What did you pickup?

 

So riddle me this...if they label the car to use Premium only and there is a vast range of "premium" octane fuel through out the country is the car smart enough to know it has 91 instead of 93 or 95? 2-4 points is a fairly wide range where in California there's a 4 point range from regular to premium 87-91. Does the computer change they way it maps the fuel if there's 91 instead of 93? Because if that's the case it should be able to change it up when it sees 87 or 89. Or i could be just talking out my a ss haha

 

I originally wrote ......
Quote:
Originally Posted by Mikey100
As a note, I just got a new vehicle with 10.6:1 compression ratio and the mftr specifically states: "Use REGULAR gasoline."


Well, I HAD to edit my original post. It's actually 10.8:1 compression ratio.

It's a FORD EDGE LIMITED, with a 3.5L Twin independent Variable Cam Timing (Ti-VCT) V6 Engine. This is yielding a very realistic (as recorded by my EDGE) 23 mph, which includes a majority of slow, in-town driving. It's sprayed with a "family car matching" BORDEAUX RESERVE RED METALLIC, which goes together like peas in a pod to the LS460, MB SL500 and SKEETER Bass Boat, all in similar colors. As was the dearly departed Vanden Plas Jag.

the EDGE is Very Very VERY Sweet, currently undergoing being tricked out now. The electronics alone make this ride Sweet as all get out ! - -

And it runs like a scalded dog, and doesn't squeal at all on REGULAR gas, which the manufacturer recommends. And by the way ...... Even with also a large oil capacity in this engine, FORD still themselves have 5000 mile change intervals. Of course, I am ditching the Dino-Class "BLENDED" Mobil 1 and now using exclusively 100% synthetic Valvoline. And yet, still following manufacturer recommendations and changing @ 5000 miles (or a little less).

(I'll use the MOBIL 1 in my SeaDoo's).

Thanks for asking, Mikey Lulejian - Lake Oconee, GA

 

"I am ditching the Dino-Class "BLENDED" Mobil 1 and now using exclusively 100% synthetic Valvoline."

Mikey, Mobil 1 markets itself as a full synthetic. How do you know that it is not? Are you confusing it with other conventional oils that they make?

 

First to answer you specifically .... No. I did not, and am not, confusing nor confused about the lubricant mentioned.
I wrote an article about this. It's in the Maintenance forum. Mobil 1 in Europe IS fully synthetic. It's a "marketing" thing in the U.S. Many people in the US refuse to believe this fact. And seriously, it's ok with me. I just wanted to express what I know is factual.
Mobil 1 is a GREAT lubricant. But when people tell me it's OK to disregard Lexus' oil change intervals "since they are using Mobil 1 which is a fully synthetic oil" unlike standard Lexus oil, then I get a little concerned.

It's just another point of controversy to never be decided. Kinda like politics. Which is why most sensible people leave it alone. Makes for increasing friendships when ya keep yer trap shut. LOL !

Sincere Best Wishes, Mikey Lulejian - Lake Oconee, GA

 

Yet it says "Fully Synthetic Motor Oil" on the Mobil 1 label, false advertising? (Class action suit in order?)

Possibly you're referring to one of Mobil 1's 'blended' motor oils?

 

Mikey, I don't mean to be argumentative, and trust me, I have no faith in "Big Oil", but what facts do you have that Mobil is lying about their synthetic oil?

 

Using regular agains premium you save around $40 a year. Considering inflation and not paying interest banks this level of saving doesn't bring you enough money for retirement