premium vs regular fuel

[xplicit_sir]

With gas prices expecting to hit $1.50/L i decided to do some research and came across this page. I've always used premium gas but gas prices are making me think twice. What do you guys think?

Premium vs regular fuel (http://www.cartalk.com/content/features/premium/questions.html#9)

[hampstor]

Try putting 87 octane into a WRX STi. It will make your 300hp car into a car that can't even pass a Neon sx2.0 on the highway.

They left the 'horsepower' argument out because they could not write a 'MYTH' about it :)

Edit: I drive a n/a car now and have no need for anything other then 87 :D

[dj_rice]

Meh, doesnt bother me much, I drive a SUV and she always gets premium anyways so...

[94boosted]

It totally depends on what your driving "hampstor" is right if you've got an STi or any other Turbo car or one that says "Premium Unleaded Fuel Only" then you gota use premium. But if your driving an N/A car that doesn't need it save your self 10 cents a Liter and put in regular.

[Redlyne_mr2]

I find premium lasts longer so the cost differences are negligible.

[xLostx]

if the manual states your car requires premium, use premium.

[dimi]

What kind of car do you drive, if you don't mind sharing? I accidentally filled up 89 in my s2k one time and noticed no difference.

[Aleks]

The manual on my 06 330I said use premium. I did for a while then I switched to midgrade and got better mileage and no loss in power. MOST N/A cars can go one grade lower up here depending on conditions.

[mikestang]

when I ran nitrous in my car, i filled up with 87 and never had a problem (with a 100 wet shot)

i remmeber it was track night and I had like 3/4 87 so i filled the lst 1/4 premo hoping it might help the octane since i wasnt going to miss it, nothing happened so i was like wtf.. ill just use 87 from now on

[CivicDXR]

Originally posted by Redlyne_mr2
I find premium lasts longer so the cost differences are negligible.

+1:werd:

[rc2002]

I actually find the opposite. Regular gets me better mileage than premium.

[Deetz]

Originally posted by richardchan2002
I actually find the opposite. Regular gets me better mileage than premium.

Me too

[ZMan2k2]

I've tried both in my truck. I ran the tank down to the light coming on, and filled up once with regular. Over the course of the tank, I noticed that my acceleration was worse, when cruising, the RPM was about 250-500 higher for the same speed over the same road, mileage overall was down 85kms for the tank, and there was generally shitty to drive and harder to start. In the manual for my truck it says I can use 87 but Toyota recommends 91. After my experiment, I'll stick with premium.

[HiTempguy1]

I actually find the opposite. Regular gets me better mileage than premium.

It should, due to the fact that the higher the octane rating the slower (we'll say more ineffecient) burn rate of the fuel. Having said that, OBD2 cars (especially newer ones) can SOMETIMES take advantage of higher octane by advancing the crap out of the timing until the car detonates slightly, then backs the timing off. Higher octane allows cars to run more ignition timing, giving you better gas mileage. So sometimes it is a wash, but for the most part running the lowest octane possible will get you the best gas mileage.

Another thing to consider is the elevation we are at. Cars that normally require XX octane fuel can sometimes get away with lower amounts of octane due to the air density difference. What it comes down to is you should run what the manufacturer suggests. They put a lot of R&D into their own motors and what they need.

[xplicit_sir]

Originally posted by dimi
What kind of car do you drive, if you don't mind sharing? I accidentally filled up 89 in my s2k one time and noticed no difference.

I drive a 00 civic sir

[bspot]

Originally posted by ZMan2k2
when cruising, the RPM was about 250-500 higher for the same speed over the same road

Lol.... someone has no clue how transmissions work.

Did regular gas make your gears grow more teeth? :rofl:

[JordanAndrew]

Premium for the win :thumbsup:
My car requires premium so I would rather pay the extra few cents per litre to be safe than sorry. Sure I'll save a few dollars every tank that I need to fill up but in the end I'm saving myself the trouble of spending a lot of money in repairs for putting the wrong fuel in my car.

[85regal]

wow.....some people need to do some research on what octane really is...thread full of ignorance...

[realazy]

Originally posted by 85regal
wow.....some people need to do some research on what octane really is...thread full of ignorance...

WOW, this thread is so misinformed...

Ok, so the octane rating of a fuel is the fuel's ability to resist knock. With 100% octane having a octance level of 100, the octane number denotes a fuel's ability to resist knock compared to 100% octane.

Some fuels like natural gas, actually has higher than 100 octance levels (approx 120), but that's another topic.

So what is knock?

Knock is the problem of gasoline engines when the end gases in the combustion chamber ignite too early ( before the spark plugs actually ignite), similar to how diesel engines work due to high compression.

The high compression causes the temperature in the combustion chamber to be too high and therefore igniting the fuel.


So if your car runs a high compression ratio, (around 11:1 and above) or in turbo applications, you would need the proper level of octane to resist engine knock.


and....That's why higher performance vehicles need the proper octane level fuel.

[rp_guy]

Originally posted by ZMan2k2
I've tried both in my truck. I ran the tank down to the light coming on, and filled up once with regular. Over the course of the tank, I noticed that my acceleration was worse, when cruising, the RPM was about 250-500 higher for the same speed over the same road, mileage overall was down 85kms for the tank, and there was generally shitty to drive and harder to start. In the manual for my truck it says I can use 87 but Toyota recommends 91. After my experiment, I'll stick with premium.

wow apparently premium changes your gearing too

[Tik-Tok]

You know what I love?

The fact that the price difference between regular and premium in the U.S. is only about 2-4 CENTS a liter, yet it's 11-12 cents up here.

Yay Canada.

[GTS Jeff]

Originally posted by rp_guy


wow apparently premium changes your gearing too :rofl: Don't you love that? Mid grade is the best though, doesn't change your gearing, but it'll give your car a bit of boost. It's like a liquid turbine for your engine.

[sillysod]

Audi A4 turbo with 87 = CEL...

Had to fill up in a small town in northern Alberta where there was no 91... made it about 10 minutes then the CEL came on and the car went into limp mode.

If it says Premium on the fuel door then run it. if not don't waste your $$$

[dieselpower91]

I think what Zman2k2 was saying is that he has to give more throttle to go the same speed over the same road with regular.

I found with my CTS-V the few times I ran regular it got worse mileage and the power dropped off noticably. The owner's manual reccomends premium but regular is acceptable.

I think it depends on what you drive. It is worth the extra few bucks every fill-up in something with performance.

[rage2]

Originally posted by richardchan2002
I actually find the opposite. Regular gets me better mileage than premium.
:werd:.

Those who say otherwise are just fooling themselves. It's basic science that higher octane deliver less power.

As for using a lower octane fuel, I would only chance it on a NA car. For those, you can go down 2 octane points in Calgary and get better mileage and performance. That's due to our elevation here.

If you head out of town towards sea level, make sure you're back on the recommended octane fuel.

I wouldn't even bother on a turbo car, they make up for lost pressure so it has the same cylinder pressures as sea level.

[03ozwhip]

Originally posted by rage2

:werd:.

Those who say otherwise are just fooling themselves. It's basic science that higher octane deliver less power.

As for using a lower octane fuel, I would only chance it on a NA car. For those, you can go down 2 octane points in Calgary and get better mileage and performance. That's due to our elevation here.

If you head out of town towards sea level, make sure you're back on the recommended octane fuel.

I wouldn't even bother on a turbo car, they make up for lost pressure so it has the same cylinder pressures as sea level.

what about a supercharged car? im running 91 in mine now, and i still get a CEL if im idling between 50-70 km/h

[BigBadVlad]

Isn't slowing the burn better for power? I'm no science wiz but I remember that a slower burn actually delivers more power because the "bang/explosion" will push the piston longer effectively delivering more power over the stroke of the piston. A quick burn means your piston will travel longer and farther without the push of the exploding air and fuel.
That's effectively what Nitrous does is it slows the burn, making the bang last longer which gives more oomph.

.02

[weeznah]

wouldnt you be able to run 89 octane with an octane booster???

[Tik-Tok]

Originally posted by weeznah
wouldnt you be able to run 89 octane with an octane booster???

That stuff is shite (mostly)

Most of them only increases by 10-15 points (1-1.5 octane ratings), and cost $6-10. You're better off just buying premium.

[ZMan2k2]

Originally posted by bspot


Lol.... someone has no clue how transmissions work.

Did regular gas make your gears grow more teeth? :rofl:

No, but when I was using my scangauge digital display, the RPM was around 250-500 higher. I assume from this, the engine is working a little harder to keep me running at that speed.

[bmeier]

Originally posted by ZMan2k2


No, but when I was using my scangauge digital display, the RPM was around 250-500 higher. I assume from this, the engine is working a little harder to keep me running at that speed.

before you get flamed to death by other member's i suggest you go read up on how an engine and transmission work together in a car..

[sugoi240]

Oh the ignorance!
gasoline is gasoline, the output is the same,

The octane rating is the gas' ability resist detonation prior to the spark plug's ignition.

Think of a clock arms representing the piston,

from 12 oclock, the piston moves round to 4 oclock and the
exhaust gas leaves through the valves, at 6 oclock the
exhaust valves close. at 8oclock the intake valve opens
and lets the o2 in w/ the gasoline (in vapor form)

at 11 oclock the intake valves close and at 2 oclock the spark plug fires pushing the piston round again.

Pre-ignition (knocking) is when the octane rating is too low for the excessive engine heat.

So instead of the spark plug detonating the fuel at 2 oclock,
it could easy detonate prior to the piston coming back up.

There is now an opposing force to your engine's rotation,
now it the engine senses this through your knock sensor, slowing your timing
and reducing your power to prevent pre-ignition.

In zman2k2 case, his engine had to work harder to provide the same power since his timing was retarded.

If you can run lower octane, it's good for you.
Running higher octane are for people who have powerful
(very high temp) cars or want smoother performance
or don't plan on changing cars too often.

[Ek9Max]

The biggest factor in being able to run 87 octane in a "premum fuel recomended" car (aside from turbo/supercharger) is our ELEVATION.

we're at 3500 feet elevation. The general rule of thumb is that every 1000' use 2 octane points lower.....

The actual compression in the combustion chamber is MUCH lower at a higher altitude. (like doing a compression test on an engine here may net 160psi, and 180psi at sea level)

I have an MDX and a TSX that "recomend" premium. But i get better power/mileage with regular....

That being said, if i go to a lower elevation, i'll put in better gas...

[gpomp]

Originally posted by rage2

:werd:.

Those who say otherwise are just fooling themselves. It's basic science that higher octane deliver less power.

As for using a lower octane fuel, I would only chance it on a NA car. For those, you can go down 2 octane points in Calgary and get better mileage and performance. That's due to our elevation here.

If you head out of town towards sea level, make sure you're back on the recommended octane fuel.

I wouldn't even bother on a turbo car, they make up for lost pressure so it has the same cylinder pressures as sea level. what would you run at 1000 ft? or 2000 ft?

[sugoi240]

Or if you like, you can advance your timing for higher elevation compensation to get more POWER

[TorqueDog]

Originally posted by Ek9Max
The biggest factor in being able to run 87 octane in a "premum fuel recomended" car (aside from turbo/supercharger) is our ELEVATION.

we're at 3500 feet elevation. The general rule of thumb is that every 1000' use 2 octane points lower..... So I could run 87?

... I'm just a touch weary. I'd rather spend the extra couple dollars and protect my (horribly depreciating) investment.

[sugoi240]

You could run 87, the question is how hot your engine runs.
If you run a bmw, in Europe, they have access to 100 octane.
I use 91 + octane boost.
The sr20det was designed w/ 93 octane as a min.

[Tik-Tok]

Originally posted by sugoi240

If you run a bmw, in Europe, they have access to 100 octane.

It's true, and anyone not in a BMW only gets 95 octane (ron+mon/2).

[88jbody]

basicaly you only need to use as high as an octane to keep your car from knocking, and keep the computer from retarding timming.

that is why diferent cars respond to diferent fuel octane levels.

alot of you will notice nothing from fuel to fuel becasue your computer adjusts the timming to componsate for the octane level.

octane cannot affect rpm at the same speed on the same road...that can only be gearing of slipage in the transmission or clutch.

it will not make you power! ever.
but if you computer has retarded the timming 6 degres dur to running low octane and you switch to high and now the timming is back to where it is suposed to be it will seem like it is making power. when it is really just allowing you to run to the full potential.

the higher the cylinder temp and compresion/cylinder preasures the higher the octane level needed to keep from detonatoion/knock.

[pinoyhero]

Here's the rule of thumb I use ... put in the gas the manufacturer suggests.

[crx/gsr]

i put premium fuel in my 1996 ford f150 it gives me a better launch at the races lol jk jk
a little off topic but what is the highest octane fuel you can get in the city, like at a normal gas station??

[rage2]

This thread makes it sound like everyone posting is an '08 haha.


Originally posted by sugoi240
Oh the ignorance!
gasoline is gasoline, the output is the same,

The octane rating is the gas' ability resist detonation prior to the spark plug's ignition.
The output is not the same. The higher the octane, the slower the burn, the lower the power output. It's 100% proven fact.


Originally posted by Ek9Max
we're at 3500 feet elevation. The general rule of thumb is that every 1000' use 2 octane points lower.....
The rule of thumb I've used is 1 octane point for every 1500ft. Oil companies are a little more conservative, you'd have to get to 6000ft elevation before they offer 85 octane as regular.


Originally posted by gpomp
what would you run at 1000 ft? or 2000 ft?
You'd run whats suggested lol.


Originally posted by sugoi240
Or if you like, you can advance your timing for higher elevation compensation to get more POWER
No, there's a physical limit to this where you would start advancing too much and pretty much "detonate" by sparking too early lol.


Originally posted by 88jbody
basicaly you only need to use as high as an octane to keep your car from knocking, and keep the computer from retarding timming.

that is why diferent cars respond to diferent fuel octane levels.

alot of you will notice nothing from fuel to fuel becasue your computer adjusts the timming to componsate for the octane level.

octane cannot affect rpm at the same speed on the same road...that can only be gearing of slipage in the transmission or clutch.

it will not make you power! ever.
but if you computer has retarded the timming 6 degres dur to running low octane and you switch to high and now the timming is back to where it is suposed to be it will seem like it is making power. when it is really just allowing you to run to the full potential.

the higher the cylinder temp and compresion/cylinder preasures the higher the octane level needed to keep from detonatoion/knock.
Wow, someone that knows whats going on! :thumbsup:

[Eleanor]

Originally posted by sugoi240
Oh the ignorance!
gasoline is gasoline, the output is the same,


gasoline is not gasoline, output is not the same. The molar enthalpy of combustion of various different blends of gasoline differs, depending on the percentages of each component in the gasoline. Gasoline is not a term for a specific substance, rather it is a general term used to describe a mixture of various hydrocarbons.


In zman2k2 case, his engine had to work harder to provide the same power since his timing was retarded.

In zman's case, he has no clue what he's talking about. At a given rpm in a given gear in a given car you will be at x km/h, period, anyone who tells you different is full of shit. (unless they have a CVT)[/B]



If you run a bmw, in Europe, they have access to 100 octane.

Pretty sure there aren't BMW specific gas stations in europe, although i'm sure BMW owners are trying to push through that legislation :rofl: . in europe they also advertise their gas using the research octane number as opposed to what we use in N.A. which is the anti-knock index aka ron + mon (motor octane number) / 2

[Eleanor]

damn, beaten by rage :rofl:

[max_boost]

Originally posted by pinoyhero
Here's the rule of thumb I use ... put in the gas the manufacturer suggests. There you go! Best post! haha :eek:

My SLK is N/A and for awhile I was only filling with 91 or 92 until one day I noticed the gas lid recommending 93 :rofl: Not sure if there were really any differences but now I only fill 94, just to be sure!.

For my WRX, 91 min. don't want to even chance it with anything less.

[rp_guy]

Originally posted by max_boost

My SLK is N/A and for awhile I was only filling with 91 or 92 until one day I noticed the gas lid recommending 93 :rofl: Not sure if there were really any differences but now I only fill 94, just to be sure!.


might be euro octane but it depends where the slk was made

[sugoi240]

Ok, gas isn't just gas, there's lots of things, but we are talk the standard gas we get in the pumps, we're not talking explosive limits, the amount of carbons, molecular structure
or usage of hydro cracking process, where the oil comes from,etc

The difference from 87 to 91 isn't that much of a difference when talking about straight regular dino juice in this city.

I also used 94, but switched back to 91+ octane boost,
I was finding I had higher knocking ratios when on 94
w/ ethanol than 91 measured on my power Fc. Your results may vary.

[sugoi240]

Quote:

No, there's a physical limit to this where you would start advancing too much and pretty much "detonate" by sparking too early lol.


And in regards to advancing the timing yes, you advance maybe 2 degrees, not 100.
It's quite obvious, but I'm glad you mentioned it cause some people may not know better.