Vanwall

I think many people are thinking about the many articles about using premium when the car requirement states regular is OK. In all those articles the writer says you are wasting your money. Note that Oil companies want people to buy premium (more profit $$$).

The 3 rd gen TL a 11.0 compression ratio requiring premium fuel. The computer CANNOT change the compression ratio.

I do not know about others but I did not buy the car with gas mileage/fuel type in mind. If it take premium so be it!

JT3

JohnDoe2, your math is a little off, mainly because you equated dollars to miles, which you really can't do with fluctuating gas prices, plus the fact that you completely ignored the 3 MPG increase with premium fuel. (Okay, maybe you didn't COMPLETELY ignore it, but I think you minimized its impact a bit.) It's better to simply use the DIFFERENCE in cost AND milage between the two grades of fuel. Here's a better way to think about it with the given numbers:

As stated, You get about 36 more miles on 91 Octane (using the supplied numbers), which is about 1.4 gallons of regular gas (36 miles divided by 26 MPG). In other words, instead of an average fill-up of 12 gallons (again, using the numbers supplied) of 91 Octane, you need 13.4 gallons of 87 octane to go the same distance. Let's say the average gas price is about $1.80 for regular gas, and about $2.00 for premium. I think that's pretty fair nowadays, especially since the difference between the two is probably really less than $0.20... but I'm trying to prove a point. The greater the difference in price, the more miles per gallon benefit you need with premium to break even. In my area, premium is only $0.15 more, so $0.20 is overkill, but of course, YMMV.

COMPARED TO A 12 GALLON FILL-UP OF REGULAR GAS, an extra 1.4 gallons of regular would cost you another $2.52 (1.4 times $1.80), whereas 12 gallons of premium would cost you an additional $2.40 (12 times $0.20). In other words, with a 3 MPG difference, and a whopping $0.20 difference in the price of regular and premium, you STILL save $0.12 per tank (I can't stress enough... I'm using the given numbers here) by getting Premium. In a year of weekly fill-ups, that's a humongous $6.24 savings by using Premium, or $62.40 over the life of the car, using the same 10-year life that JohnDoe2 used. In other words, you don't SAVE a thousand dollars by using regular, you actually SPEND sixty bucks more.

I figured out once that with only a 2 MPG difference, you about break even by buying premium gas. Since virtually everyone agrees that premium gets you better fuel efficiency in high compression engines, there simply is NO REASON to use the cheaper gas.

Of course, as I said before, YMMV, so if your car is one of the weird ones that actually does BETTER with regular fuel (which, by the way, is virtually ANY car where the manufacturer has set a minimum octane rating of 87), then this whole argument falls apart, but on the vast majority of TLs out there, you'll actually save money in the long run (or at least, lose very, very little) if you use premium.

Aegir

Valid question that deserves a valid response. The timing curves for the TL were built based on the assumption that 91+ octane fuel will be used. If lower octane fuel is used, the timing advance will be too aggressive. This will result in detonation. Once it occurs, the knock sensor will detect it and retard the timing until it goes away. This will result in reduced performance - both in terms of power and efficiency - throughout the engine's operating range. It's probably a valid argument that much if not all of the at-the-pump savings is cancelled out by the loss of efficiency - not to mentioned the possibility of increased engine wear.

It is important to note that even though the knock sensor is preventing occurance of sustained detonation, the engine is repeatedly exposed to detonation as the knock sensor detects it and the ECU 'catches up' with what is happening in the cylinders. This cycle does not happen just once, but countless times as your engine runs through its normal operating cycle. Periodic tankfuls of low octane may not add up to engine damage, but running the engine through this cycle for tens of thousands of miles is bound to lead to increased wear and perhaps even component failure.

Here is a dyno test that shows two similar cars on the dyno - one with 89 octane and one with premium. It's not a Honda example, but it is certainly applicable. http://www.dynospotracing.com/octane.htm

JT3

Something I forgot to note in my earlier post... I chose $1.80 for regular gas, because that's currently quite a bit below the national average, but not ridiculously low. However, as the national average increases (which, realistically, it's going to keep doing), the cost of regular gas goes up, but the DIFFERENCE in cost between the grades remains fairly constant.

Using the same numbers, an additional 1.4 gallons of regular at $2.00 per gallon equates to an extra $2.80 (instead of the $2.52 with the $1.80/gallon gas), whereas ALL OTHER numbers remain the same (since premium would then cost around $2.20 per gallon, keeping the $0.20 difference constant), so instead of a $0.12 savings per tank with premium, you now have a $0.40 savings per tank! In other words, as the average gas price goes up, you save EVEN MORE by buying premium gas for the TL!

epl16

.

SouthernBoy

To Mocoso;

Who the hell sells 93 octane fuel? Every station I've even seen here on the southeast coast. Our stations are 87/89/93.


I also mileage tested a car with differing octane fuel. Both tests were with Amoco. The car was a '94 Honda Accord EX 4-cylinder (sixes were not available until '95). With an 8.8:1 mechanical compression ratio, the car was tuned to use 87 octane. So on a long trip, I primed the week in advance (to make sure I had a "clean" tank) to use 89. The result was lower fuel economy and less power. The reason was that the higher octane fuel did not result in as complete a burn as did the 87 octane.


Every reputable "expert" I've ever heard or read regarding this subject comes down with this. USE WHAT THE MANUFACTURE RECOMMENDS. Now with some, this recommendation has some leeway while with others, they are quite specific with their recommendation. Ours clearly states use 91 as a minimum. In my area, we don't have 91 octane fuels so I use 93.

Finally, I couldn't agree more with the comments of JetJock, GaleForce, and cblackburn. It's like buying a powerboat. If you have to worry and ask about fuel economy, perhaps you should consider a sailboat.


And to zcarguy;

Hell, I've always been desparate for more power. That's the way of gearheads.. the way we're wired. Ever since I was 18 and bought my first car (brand new, no less), I have wanted more power. And why not? What's wrong with that??

JohnDoe2

My "math" was a simple estimate on the cost benefit of premium gas.

It's valid and it makes a lot more sense than your convoluted attemp at misdirection.

Fond Regards

JohnDoe2

fla-tls

That's not a very good comparison, SouthernBoy. An engine with 8.8:1 compression ratio vs 10.5:1 (on a Type S) or 11:1 ('04/'05) will respond differently to various octane levels.

Once the computer in a Type S or '04 senses pinging or detonation it will retard the timing. The '94 Accord probably only requires 87 octane gas to begin with.

automophile

Sure, you can run cheaper gas without ruining the engine - But it will COST YOU MORE!!!

I have run extensive tests with my previous car. When you run lower octane, the now retarded engine timing also cuts your gas mileage.

Ine the END, you pay MORE per mile with the cheap gas.

It is a FALSE ECONOMY

SouthernBoy

To fla-tls;

That wasn't my point.. perhaps I should have been more specific. I was just trying to relate an experience I once had with trying a higher octane fuel than the manufacturer recommended for the engine. The results I saw were what I had expected. Less fuel economy and less power.

Yes, comparing that Honda to the new TL would be like comparing oranges to apples.

bigman

if you throw in 87 every once and a while, the car would just retard timing. It would prolly switch over to limp mode as well. you may get some pinging at wot.

fla-tls

Got it - cool. Yeah, using gas higher than the recommended octane rating does nothing more than cause more pollution and potentially decrease mileage. I've heard that higher octane fuel actually has less energy than lower octane fuel (contrary to popular belief).

I think it's best to stick to the recommended level and no more - if you have it available in your area.

JT3

I appologize if I sounded condescending. That wasn't my intention. By your own admission, yours was an estimate, which is fine, but I was trying to show mathematically (and isn't math always convoluted? ) how the difference of a mere 3 MPG can make the premium gas actually cheaper in the long run, even though the $0.20 more per gallon makes it seem like you're paying more. Quite simply, the tank only holds so much gas, and if you're able to go 39 miles further on a tank of premium (assuming an average 13 gallon fill-up), it means more fill-ups for the regular-gas crowd to go the same distance. In the long run, those extra fill-ups will more than compensate for the extra cost of the premium fuel.

You say yours was meant to show a cost benefit of premium gas, but your final point was that you save $1000 over a 10 year period by buying REGULAR gas (showing, technically, a cost benefit of regular gas, not premium), which is simply incorrect with the given gas mileage figures.

I guess we'll have to agree to disagree here, but I assure you, my figures are exact and accurate.

xiaxia

Here is the math that is both simple and accurate.

Assume one drives 12000mi/year on highway, gets 26mpg on regular, 29mpg on premium, and the price is $1.80 for regular, $2.00 for premium:

annual cost using 87 (HW): 12000/26*1.80=$831
annual cost using 91 (HW): 12000/29*2.00=$828

So, as JT3 said, you actually save a few bucks buying 91. Note that the above are numbers for highway driving. For city driving, assume one gets 22mpg on regular, 24(?) on premium, buying regular does save some money, but not much:

annual cost using 87(city): 12000/22*1.80=$982
annual cost using 91(city): 12000/24*2.00=$1000

SouthernBoy

To fla-tls;

Actually, higher octane fuels produce more power than lower octane fuels.. when used in engines that have been designed, built, and tuned to take advantage of this fuel. All octane really does is to slow the burn rate of the fuel down (really makes it harder to ignite through what's called "compression ignition".. diesel engines utilize compression ignition.).

Burning a higher octane fuel than your engine is design for will result in a loss of power, less fuel mileage, an increase in carbon builtup (which will actually raise your mechanical compression ratio a little, requiring higher octane), and less of the fuel actually burned in the cylinders.

Ron A

I have always believed, from what I have read, that octane has nothing to do with the production of power, but allows higher compression by suppressing the preignition which causes knocking.

I googled on octane and found this, which explains a little further.
http://auto.howstuffworks.com/question90.htm

Since I have been in this forum, which I joined in Fenruary when I got my 04 TL, this subject has come up almost every week, it seems.

Here is a consensus of what comes out of these threads:
1. If you can afford to spend 35K for a car, you can damn well afford to buy premium
2. RTFM, which recommends premium 91 octane fuel
3. Buy what you want, it's your car and you can ruin it if you want to
4. Why are we even talking about this and who would consider putting regular fuel in their baby
5. I used regular in my (insert your car here) so why can't I use it in my TL
6. Premium gas is just a way to separate the fools from their money

Aegir

Link is unrelated. I don't think that there is any consensus here, but I do agree that this is a summary of the most common points.

Moderator's note: I put the wrong link in, and have corrected it in my original post. The correct link is http://auto.howstuffworks.com/question90.htm Sorry about that

JohnDoe2

I think points one and six are related

KilroyR1

This is not true. Octane has nothing to do with the actual burn rate of gasoline. It is a measure of resistance to pre-ignition. Additives that affect the octane rating do not change burn times. Look into race fuels like Nutec and VP, the fuels that increase power (through higher burn rates) have similar octane ratings. It is a different additive package that produces the power gain.

Don

ResearchFreak

In the on line brochure for the 04 TL we recieved from a dealer it specifically says that 91 Octane is recommended, but "gasoline with an octane number lower than 91 may be used with reduced performance". Sounds like permission from Acura to use the lower octane if you want to.

Azuki

TL is my second car, I used to own a Prelude. For both cars I have NEVER used anything lower than 93, I would eat cup noodles all week and will still feed my car with the best fuel possible, I guess I am a bit weird

There are always good deals on prenium gas even with name brand like Shell and Mobile, go around the block a few times and you will find a significant difference in price (the biggest difference that I found recently is 17 cents per galon). If you spend some time you will be looking at paying for medium grade but getting prenium fuel.

Be good to your TL, I think gasoline is the easiest place to keep your car in good condition. Just my 2 penny

jdone

As we established long, long ago feel free to use 87 octane. It won't harm your car. However, you will get about 8% lower peak HP and about 2-3 mpg lower fuel economy. Buy why would anyone do this?

terse

you should just put water in it...instead of the 87 gas...

SouthernBoy

To KilroyR1;

Actually what you said is basically the same thing I said so my statements are true (if we are to believe that both of our statements are true). Compression ignition is one of the ways (mechanical) in which pre-ignition and possibly detonation are instantiated. Another way is having the initial timing set too high (too much advance). Higher octane fuels are able to resist this process up to a point.. and that point is where THEY will suffer the same fate as lower octane fuels will.

As for burn rates of fuel, gasoline in particular, there are a host of variables involved here. Weather/temperature, ignition timing (is the initial timing too advanced?), the engine's mechanical compression ratio, vehicle load, and driving conditions to name a few. The only reason that higher octane fuel helps an engine to produce more power is because the requirements of the engine and its components are such that the use of a lower octane fuel will result in pre-ignition. Using a higher octane fuel in an engine system not designed for it will not produce any more power. In fact the reverse is more than likely going to be the result.

Pro Stock John

Great thread.

This thread is worthy of keeping in an archive because of the cost comparisons.

A few other things to keep in mind... Now with GM cars there is a reduce power mode. If the pcm detects a lot of knock retard over and over, it will put the car into a reduced timing table. I would not be suprised if this could happen to a TL as well. In a GM like my Formula stock timing advance at WOT is 27 degrees, and the reduced timing is like below 15.

Octane suppressed pre-ignition and does nothing to make power.

If you were to run 87 constantly and get audible pinging for a lot of miles you in fact can do damage to your spark plugs, but also to your valves. Audible pinging is very very bad.

If you were dead set on running 87 I would look into running plugs that were like 2 heat ranges colder than stock.

The Camaro/Firebird guys have debated octane in the past but nobody ever bothered to compare the actual cost.

randyblochowitz

HEY GUYS. I have run 100 octane and 87 and 89 and 91 and 92 and 93. They all work great. I have a 99 tl and prior to the intake I put on wich just rocks. I recommend that everyone who owns an acura tl go and buy a metal intake pipe and a nice filter and if you have any questions I can tell you how to make it fit. I have also removed the stero and know alot about the stereo system. let me know if you have any questions. I will also be adding 20s to the mix next week. ITS GOING TO BE SICK---randy[FONT=Comic Sans MS][SIZE=7][COLOR=DarkGreen][B]

Houston

To anyone asking, "why would u buy a 35,000 dollar car and be cheap on gas?", did u ever stop to think that maybe he bought a used TL for 11,000? But yeah, it is only a 5 dollar diffrence and that's worth the power, gas mileage, and to keep your engine from pinging. Just stick to 93 octane.

Babnik

Well this thread was started in 2004 when the 3rd gen TL had just come out, so there were definitely none for 11k then. Even today you can't get a 3rd gen TL for 11 unless it's been wrecked.

In any case this has been answered many times. Yes you can use 89 or even 87, no it will not damage your engine, but it will reduce your performance quite noticeably, and your engine will burn it up at a much faster rate so it's actually cheaper to use 91 or 93.

01tl4tl

91 minimum for a reason- 93 is thats what the sell at your altitude and latitude
Its possible to burn a valve- pinging is only a symptom of other problems realted to early detonation of the fuel mix

Run seafoam or other fuel cleaner 1 can to 1/2 tank-thru the system if you run 87
150 bucks average `savings`over a year- on price between 87 and 91

no need to run 100 octane unless its free- a normal TL- not turbo or supercharged, will not reap any reward in mileage or power for cost.
Hotter gas may clean the pistons for you but thats it- I work with race gas at the race track- I know- we have signs to discourage the street cars from buying higher octane than they need- it simply wont do them any good at 6-10 bucks gallon~
turbo or supercharged can use the 100+ octane fuels

BEAR-AvHistory

You need to read up on why/how various octane ratings function.

That being said in simple terms higher octane then required can't add horsepower that is not there but lower octane then required can take away from horsepower that is there.

As for the grade question NC stations have 87, 89 & 93.

01tl4tl

the bearcat run 115-145 still?

this thread is 4 years old and a lot has been learned in that time, including a few ziners burning valves on 87-
now was the 2-3 dollar `savings~per tank by not using the required gas- whats that $150 a year?- worth the $$$$ 2500 in damage to the engine?

Babnik

Is it certain that it was the fuel's responsiblity for the valves?

T Ho

Pre-ignition and detonation are one of the few ways to actually burn a valve. Breaking a valve spring is another. Beyond that, excess power adders.

If the cars were stock, then long-term detonation damage is the likely result.

Modern electronics go a long way in making engines work on fuels that they just would not have run on 20+ years ago (my 9.5:1 carbureted 1980 Z28 *hates* 87 octane), but an 11:1 engine needs premium, IMO, for its long-term health.

csmeance

wow, old thread revived by a new poster...

TLAdvanced

iTrader: (4)

WTF???

SporkLover

Prostock John posted info from the LS1 world..... I have seen the debate rage over on LS1Tech. Yes there are "detuned" PCM tables for detonation mode......

Not worth it IMO..... the engine was designed for the higher octane and it is what the manufacturer recommends...... why go against that? If you operate your vehicle beyond the limits of their recommendation you put yourself at risk for warranty work!

Adobeman

Well, the "TV Experts" were on last night talking about how to save money and gas and they started the old "use regular" rant. The interviewed a bunch of person-on-the-street bafoons saying things like "my daddy said to always use premium cause it's got less gunk" and "it's got more good stuff for my engine" I think it's clear that most of us that still use premium aren't doing this for those reasons.

What was most interesting is that the talking head on the TV has revised their "use regular" rant to say "use regular unless you have a higher compression motor and follow your owners manual".

Adobeman

Well, the "TV Experts" were on last night talking about how to save money and gas and they started the old "use regular" rant. The interviewed a bunch of person-on-the-street buffoons saying things like "my daddy said to always use premium cause it's got less gunk" and "it's got more good stuff for my engine" I think it's clear that most of us that still use premium in our TLs aren't doing it for reasons like that.

What was most interesting is that the talking head on the TV has revised their "use regular" rant to say "use regular unless you have a higher compression motor and [furthermore] follow your owners manual". We've got a higher compression engine and an owners manual that says 91. I knew this before I bought the car. Nothing's changed. 93 (can't get 91) is still 20-ish cents more than 87 in my market. B-F-D! It's not the delta in price between the grades that's killing people, its the base price of the lowest grade.

ggesq

iTrader: (1)

There is no need to rehash this debate. Thread closed.