acuraTL44

Would it be OK if you put 89 octane gas inside the TL instead of 91 or higher? Would this harm the engine? I do not have the TL yet, but I think I should know ahead of time. Presently, I have a car that requires premium gas and I've been puting plus(89 octane) in it for as long as I can remember and the car runs just fine. Any help will be greatly appretiated.

WDP-Acura TL

Its recommended that we use premium octane . You will get better performance than using lower octane gas. The car won't transition to each gear as smoothly either. I tried it and didnt like that my cars acceleration slowed down a bit. But its all your decision what you want.

SouthernBoy

This question has been asked SO many times and invariably leads to this question:

Why would you spend $33 to $35,000 for a car then worry about the grade of fuel to use? It just makes no sense. If the cost difference 91-93 octane and 89 octane is prohibitive, then logic would seem to dictate the price of the car, insurance, taxes, and other items would be astronomical.

Not a flame, but if this is a concern for you, perhaps another car may be better suited to your wants and needs.

ou sig

very true, when you think about it, it comes out to maybe less than $100 more/year and thats if you fill up everyweek.

misterPT

I've actually tried using gas lower than 91 and I'll tell you it isn't worth it. Performance decrease was VERY noticeable and the worse thing was my gas mileage was also bad. I usually get around 19-21 with 91 octane gas, but with 89, I got 14-15 mpg!!! I thought it might be wrong some how so I busted a move and filled it again. This time, I got around a 13.9 mpg! Filled it back up with 91, and I'm right back to 19-21 mpg with mainly city driving.

gochan

damn, 14-15. how crazy you driving?

misterPT

Can't help the feeling of hitting VTEC ! But I drive the same as with my 19-21 mpg on 91 octane with city driving (hit 34 mpg when driving to LA ). When using 91, I've NEVER gotten this low of a mpg no matter how hard I drive. That's why I'll be sure to NEVER use 89 octane in a car that requires 91 octane again.

Neorick

https://acurazine.com/forums/showthr...ghlight=Octane

Please use "search" before creating new post:

acuraTL44

OK, if its less than an extra 100 dollars a year than thats great! I will not at all put lower than 91 octane in the TL.

cpurick

Anytime a car suggests high-octane fuels "for best performance," you should interpret "performance" to include fuel efficiency as well as horsepower. Even if you can fill the car with cheaper gas, your real savings have to consider that you'll burn the cheaper stuff faster.

Remember, at the end of the day it's not dollars per gallon, it's dollars per mile. When you look at it that way, there's a lot less to be saved by using cheaper fuels.

SouthernBoy

Just like everything else in life.. things come with a price. Some years back when I was narrowing down my choices for our first boat, I asked the question about fuel economy. That's when I was hit with the, "if you have to ask about how much fuel it burns per hour, you're probably not ready to buy a boat".

This is good advice and can be applied to automobile purchases, too. The way I see it is that there are basically four types of automobile buyers out there. Remember, these are generalities.

1. The washing machine buyer. To him or her, a car is just a means of transporation.. something to get you from A to B.

2. The utility buyer. These are the van, SUV, and truck buyers. They put their vehicles to work, towing, hauling, or something else of a similar nature.

3. The yuppie scum buyer (I am borrowing this term from a man I once knew). These are the people who buy "symbol" or "status" cars without really having any knowledge of what they are buying. They just want the aura of status they believe the car will afford them.

4. The driving machine buyers. These are the people who take their choices seriously and almost believe cars have a soul (forgive my God on this one). To them, a car is far more than just a hung of metal, plastic, and rubber. It's a part of them.

The fuel-conscious people will probably fall within numbers 1 and 3. Utility vehicles, by virtue of design, are going to burn more fuel. As are performance machines. The number 4 buyers could care less about fuel economy. To them, if their car does get decent mileage, it's icing on the cake.. not something that will make or break their decision.

mikef723

I was told by my dealer to put mid grade in. First tank my MPG was really low so I can understand what you said MisterPT. From now on its premium for me.

Road Rage

There is no way that the diff between 91 and 89 will result in 20% or more change in fuel economy - that is absurd.

In my files somewhere, i have a white paper I got from my pals at Honda Eng'g in California, and it showed less than 10 HP/8 pounds TQ between 92 octane and 89, in an NSX*!! In racing, that will add up to fractions of a second a lap, a big difference. For highway cruising, almost no difference. Premium fuel often has more detergents in it, so over time, it is possible that running 89 will allow power robbing deposits to form on the fuel injector pintles, the intake valves, and even the piston crowns. That could lead to perhaps a 5-8% reduction in fuel economy, but you'd notice idle problems first, and a lag at power tip-in.

*Honda saw the reduction coming in octane from emissions policing in states like California, and adjusted its engine designs early o have plenty of field engineering under its belt. Advances in the precision of fuel metering, injection, and intake swirl have also reduced the importance of high octane, even in cars with compression ratios that in the 60's would have demanded Sunoco 101. Yeah for progress!

Now I run premium, because the miles i drive do not make it a big deal, and fuel is relatively cheap in Virginia. But if I were a salesperson, and drove easy highway miles to the tune of 30-50k a year, i would definitely run 87 octane most of the time, and use the same quality fuel additives I do now (see my Journal entry for info on that).

JT3

There was another thread on here where a couple of us showed mathematically how a difference in only 1 or 2 MPG would completely offset the price difference making premium fuel actually CHEAPER than the lower grades.

I don't want to post that whole argument again, but the bottom line is this: The TL gets, on average, 2 to 3 MPG better with premium (91 octane) than with regular unleaded (87 octane), and 1 to 2 MPG better than with plus (89 Octane). This small increase means that you drive further on the same amount of gas... or, put another way... you need more lower grade fuel to go the same distance. That extra gas actually ends up costing MORE than if you'd simply gotten premium fuel in the first place.

If you want the math, I can post it again, but suffice it to say, there is ABSOLUTELY NO REASON to buy the cheaper grades. Premium is better for the car (since it's tuned for that grade), and you'll actually spend LESS money over time with premium. Even on a single tank, you'll get enough extra milage to cover the $0.20 (or less) difference in cost per gallon.

SouthernBoy

Hey Road Rage;

It was Sunoco 260 in the 60's. At one point, this fuel reached 104 octane, but the method by which octane was rated was different then than now.

Road Rage

I don't buy the MPG difference - I would need to see some controlled, repeatable testing protocols. Placebo effect is a well-known phenomenon - and the basis for all those miracle gas and oil additives, or even "The Tornado" - people make all sorts of claims about the "huge" improvements they see. Notice that the mfr does not make the claim, they just let people on the videos do it. That is why double-blind testing is the basis of scientific studies - so neither the tester nor the partcipant knows which is which, and then a placebo is often used as a control. The fact is, people will adjust their driving behaviors to achieve whatever result they want - they put on a new K&N, and the car "leaps from the stoplight". Never mind that the low RPM advantage of the filter is zero.

The arguments made here would be more compelling if there were a large variation in thermal output between grades of gasoline, such as 87 to 93. In fact, the differences are slight. Only when an engine would be prone to constant detonation, and hence the KS would be retarding the timing frequently, would the effect of octane be large. Cruising on the highway does not tax the engine - in fact, probably no more than 30-40 HP are being used, and the KS not deployed at all. So for highway crusing, high octane provides no benefit. Zip. Zero. Nada.

As I already posted, Honda found a handul of HP difference in the NSX - that would result in perhaps a 1-2% effect on MPG, tops. Certainly a quantum difference than a full 1-2 MPG. Not even close.

The fact is, the variance between 91 and 87 is at most, 3%.
3% of 25 MPG is .75 MPG.

This and the referenced JT3 post may have good math, but good math based on incorrect constants is bad math. Both of these threads are exemplary examples of the effects I described above:
1) No scientific protocol
2) No scientific rigor
3) Plenty of opportunity for known psychological effects to negate the results

I would suggest anyone that thinks I have lost it, am making up the reports I got from Honda themselves, or am a blowhole read this:
http://www.epa.gov/otaq/cert/dearmfr/vpcd9701.pdf

Another excellent source of factual and on-topic info is Chevron:
http://www.chevron.com/prodserv/fuel...rmance/pg4.asp
Note that they mention that anecdotal estimates by drivers are often way off.

Run your math model again, using .25 to .75 MPG, and advise us if there is still no valid reason. Thanks.

dashotgun

I think all of you are missing the point seems to me I would rather rely on the fuel with higher octane to avoid knock rather then the knock sensor. At least in turbo charged applicactions knock can get expensive very quickly.

fsttyms1

but what your missing here is the long term effect. the car has to work over time to get it to run normal, there are more polutants when running lower due to the ar not being as efficiant, there is more stress on the cat and o2 sensors more carbon build up in the intake manifold (which i have seen on the TL where people used 87 instead of atleast 91.. and dont tell me you will get better mileage with 87. i drive on average 50k a year withthe tl and i have seen large decreases in mpg when i have had to use 87 over 93.
bottom line you spend 30+ thousand on a car, being cheap at teh pump isnt going to save you any thing in the long run!

Road Rage

I covered everything you mentioned - you obviously either did not read it, or did not understand it.

"More stress on the cat and O2 sensors" - what are you talking about, and cite your sources.

ndabunka

This car is DESIGNED to use 91 octane so USE it! Anything less will give you crap for MPG (as has been demonstrated numerous times). If your not going to put the right fuel in it, the DON'T buy it. Go buy a POS Audi or something...

Rae is normallt "spot on" with details but I don't think he has tried the lower grade fuel in this car yet. If he did, he would see the same thing the rest of us are noticing. It MUST have something to do with the tuning. The MPG Sucks on these things unless run at the proper level.

SouthernBoy

The one area where us men screw up is exaggerating things; cars and guns being at the top of the heap. I can't tell you how many times I have heard people screw up telling me about the "mystery" or "special" engine Chevy or Ford made and that they knew some who had one. Well certainly, there were "special" engines and packages the car companies produced, but when you hear some of the stories I've heard, you know you're listening to someone who knows little or nothing about cars. Like a '64 Goat (Pontiac Tempest LeMans with the GTO option package) which was so powerful, it would pull wheelies with street tires. Right. Or the Plymouth station wagon with the 450 CID Hemi (Chysler never made a 450 CID Hemi). Just a couple of weeks ago, someone was telling me about a Ford 426. Ford never made a 426. They made 406's and 427's and 428's and 429's, but never a 426. And on and on.

Then with guns it gets even more interesting. The old .45ACP will blow a man off his feet. BS.. just plain BS. Or my neighbor who insists he can hit a flea's eye (which one?) at 100 yards with a rifle. Oh, he very rarely shoots, by the way. In 1968, I was at a party and I told someone my wife was going to give my a Ruger Blackhawk .357 revolver for Christmas. This guy asked me if I had ever shot a .357 before (had to find out if I was fresh meat). I said "no" so he proceeded to warn me to tape my wrist otherwise the "kick" could break it. God, I didn't know whether to laugh or cry. Fact is, there isn't a handgun made that will do this.. not even the SSK hand cannons in .338 Winchester!

We men think we have to know it all whether or not we do and are reluctant to admit it when we don't know things. So we put our foot in our mouths from time to time. There is no shame saying, "I don't know" but there is a real danger that if you tell something that is not right, you might get caught by someone who does know.

I was going to add my 2 cents to Road Rage's comments on another post about timing belts versus chains. I have a bias against timing belts and interference engines, but I read Road Rage's post and learned something. While I still have a bias, I'm not opposed to saying I picked up another point of view.

Best thing about this site, and similar sites, is the exchange of information and the learning that comes from it. Fuels, oils, tires, maintenance, and operation techniques shared can help us all.

Road Rage

Nice that a man of your obvious reasoning powers is here to tell us what sux and what does not, and what car we should buy if we do not agree with your completely unsupported spouting. That you have intrinsic knowledge of the MPG effects of octane that is contrary to the EPA, trained engineers, and certified subject matter experts is quite remarkable. Plus, the tone of delivery really does add a lot of class.

"Anything less will give you crap for MPG (as has been demonstrated numerous times)."

Crap and sucks - I missed those technical terms from my time in the 2 eng'g schools I have degrees from.

Please cite one authoritative post not based on someone's opinion that supports your "numerous times" assertion.

It is interesting that when one ask for citations to support all these expert opinions, they cannot. That speaks volumes. Talk is cheap.

dashotgun

before this thread degenerates. hey Road I repect your engineering degree the point is that these are! not an inexpensive car, intended to to be a sporty luxuary car. I am having a hard time with someone purchasing this type of car and then worrying about the few cents of difference between 89 and 91. It seems to me that they would be happier with a different kind of car instead. I suppose if you are cruising on a flat interstate then buying the 89 is okay for most of us I want the extra performance you woould get formt he 91 in the typical mixed drivign scenario occasional wot, up hills etc. AS I mentioned I also do not want to rely on the knock sensor instead of the fuel to avoid detonation. There has to be some benefit from the higher octane or Honda would not require it in fact it would be a selling point ( it only needs midgrade to get hi grade performance)

Teh Jatt

i always put 87... saves me and increase some power

JT3

What RoadRage says makes good sense, and I definitely can't prove that lower grades decrease gas milage -- especially on every car.

All I can say is that I was originally using 87 octane, and without changing my driving habits at all, switched to 91 octane, and saw about a 2 MPG increase (figured by miles driven per tank divided by the number of gallons pumped). Could there be a placebo effect here? Sure, but in my mind, I'm seeing the MPG difference, which mathematically adds up to saving me money. At the VERY LEAST, it makes me FEEL like I'm not LOSING money, which enables me to feel good about putting in the recommended grade.

The bottom line, I guess, is that while pure highway driving may not make any difference, we don't ever -- or hardly ever -- drive that way. I used to get about 19MPG with my "mostly in town" driving, and now I get 21 to 22. I'm not saying that ALL of that is the grade of fuel I'm using, but I gotta believe that SOME of it is... so I'm gonna stick with the 91 octane, until someone can show me the scientific evidence that proves I'm wasting my money. In that regard, I agree with RoadRage 100%.

ensley696

Only 93 Chevron for my baby. She don't like to drink anything else.

misterPT

Sorry if my post seemed like I exaggerated, but what I got was true (to my car at least). I was extremely surprised at how 89 gave me such low mpg. If it counts, I did try filling up 89 about 3 times and all I do is city driving. The best I got was 15.5 on the 3rd and last time I filled it up with around 3000 miles on the car. With 91, I've never gotten anything lower than 17 mpg.

Road Rage

dashotguin and JT3 - I am cool with whatever people do - I was trying to answer the guy's question, but like many things, a little factual posting gets some people to switch the issue. (Not you guys). That is an old trick of debate, but RR knows all the tricks. When one is caught being an "air blowhole", and switches to "if you cannot afford to buy premium fuel, go...." is pretty lame. I can afford lots of things, but that is not the point.

Let me switch tack, to allow a "synthesis" of thought. One of the reasons that aftermarket "chip" tuning can be beneficicial is that the mfrs leave a fair amount on the shelf, so to speak. If you read the EPA letter I cited, you should be able to infer thatby reading between the lines. The EPA wants to reduce the perf gap between 96 and 91, analgous to 92 vs 87 in "real-world" octane. Now, how do they do that? Primarily by reducing the amount of spark timing. High compression is not a variable, can't mess with that. But the amount and where the spark advance begins on the RPM curve allows a lot of play. The mfrs tune spark timing by a few factors
- the fact that octane demands rise as the car ages
- the fact that it has to allow for the worst case scenario - a moron driving up a hill in 6th gear in 100 degF heat
- the fact that some people will use really cheap fuel, that may not meet its stated octane, let alone have the proper additives needed to maintain good performance.
-some places, like California, do not even have 93 octane
etc.

My SVT Cobra picked up huge, measurable HP/TQ by having a high octane spark map programmed into my car (1 of 3 maps: street, high test, and race fuel). But our Hondas have compromised fuel/spark maps, to meet EPA direction, emissions, fuel economy, and longevity targets.

So there is little or nothing to be gained by using higher than required octane, and not much to lose at the other end, either; the mfrs have "Bell Curved" the octane demands to meet the EPA's requirements, and reduce their warranty claims. If they thought they could get 1-2 MPG across the board by upping the octane spec, they would. Between that, the controlled tests I have seen, the EPA letter, and Honda own internal tests I have on the NSX, I think I cxan make as good, or better case, than the anecdotal evidence JT3 offered - not doubting his honesty in any way, but people may think they are driving identically, but as Southern Boy and I have pointed out, they often are not.* Chew on that for a while.

Most of the time, I use Chevron 93, by the way (there, I have been "outed"). I also use Red Line SI-2 fuel additive regularly. But if I regularly drove easy highway miles, I would very likey go with 87, because I do not like to waste things, even though i can afford to - it is the same reason i added isnulation to my attic, and upgraded to UV/IR effective, and argon "dead zone" windows for $30k last summer.

use what you want, but ther answer to the question of "can i safely use 87 octane?" is yes, with the limitations and qualifications I mentioned. That I stick by.

*Remember the runaway car "unintended acceleration" phenomenon of 15 years back? Audis and other cars all of sudden were taking off on their own? 60 Minutes do a hatchet job on Audi, and their sales plummeted. People swore they had their foot on the brake - no doubt. Well, i posted then, that ever car has stronger brakes than engine. if you jam on the brakes, and floor the acclerator, eventually the car will stop. NHTSA's final report said that the claims of unintended accleration were "unfounded, and related to driver error". But at the time, everyon thought I was nuts, and insentive to the poor people who had lost loved ones to the "devil car's", as Ms Weiner (I kid u not) said in her testimony against Audi in Connecticut. She sued many times, and lost many times - the last time she sued Audi, the judged fined her for "frivolous prosecution". Facts, my firends, facts.

I saw it myself once, at high eprformance driving school. We ran 3 people in the cars: instructor, driver, observer (other student). oh yes, there was a video camera catching all the pdeal movement. Anyway, this guy is driving, i am in back. He goes into a corner too hot, and the instructor screams "brake in, hard, NOW!!!" and the guy hits the gas pedal, putting us into a spin that nearly flips the car. Instructors hate that, The instructor was fuming, and drove the car back - all the while the guy wa ssdaying "I had my foot on the brake!" - but when he saw the video, he became silent, and remoresul. The point is that "cognitive dissonance" exists, and is a strong human motivator of behavior. So is "placebo effect". TRhat is why when i see a huge economy gain claimed, that flies in the face of all reason, I have to question it - but that is questioning the technique, not the person - there is a huge difference. I will not suffer an idiot, but I am polite while lambasting the technically illiterate.

MR1

This thread appears on lots of forums.
For what it's worth, I keep reading in the thread - ACURA REQUIRES 91 OCTANE.

I must admit that I don't have my car yet but my sales book, on the Specifications Page says - RECOMMENDED FUEL...PREMIUM UNLEADED 91 OCTANE, slight difference.

I can afford the car, I can afford 91 octane. I tell myself and my wife, every dollar I spend here, I can't spend there. Sometimes I'll use 89, sometimes 91. Whatever makes you feel good, do it.

SouthernBoy

Yeah, bottom line.. it's your car, so do as you please, right?

Teh Jatt

i was only kidding

Road Rage

One would hope that anyone who got this far into the postings would have figured that out, even if we disagreed on the rest! But you almost got me for a second. Ha hahah. Good one.