I just read that some of the Pacific Coast Highway in Ca (not exactly sure where) is now in the ocean.

 

Yikes. Looking at http://www.kionrightnow.com/Global/story.asp?S=14266943 it seems like the detour is really long. And to think that I had driven on that particular road/lane before and now it's gone. It's going to make me wonder about the road beneath me when I take that road in the future.

 

I have put in 87 before and don't really notice any big differences in MPG or power except on long trips on the hwy. Stop and go traffic seems unaffected by the change from premium to regular.

 

This I have not heard of.
Source?

 

I'm the source. Back when i owned a 98 prelude SH. I had popped a brand new timing belt. Honda knew exactly what RPM it broke. Luckily Honda had sent out a batch of faulty belts.

 

Personally I do not notice any difference with traveling on highways either. I do mostly highway driving and travel from NC to NJ and back every few weeks. Use regular gas with no problems after almost 122,000 miles.

 

I currently own a 2007 TSX, and I've only put 93 octane in it since brand new. The car currently has 44k miles, and I have yet (knock on wood) to have any kind of an engine problem.

I figure that any kind of an engine repair is going to cost a lot more than the extra $2.60 I spend on 93 octane gas.

But, to each their own

 

i have an 06 tsx and since i got it used 93 but now that price is are rocket high im uusing mid-grade which i do feel a little sluggish but use 91-93 once a month and cleans out bad fuel. comsumer repots that its not bad that we use mid-grade because our cars are equipped wit sensors that adjust the fuel burn and timming. you just save money.

http://www.edmunds.com/fuel-economy/...d-premium.html

the next link has a good video

ride bikes lol

http://auto.howstuffworks.com/premiu...y-vehicles.htm

 

^^This article summarizes everything except the one and only important question to me:

What are the long-term effects of constantly running a gas lower than recommended?

And I'm not interested in anecdotal, "I've been doing it for 60K miles and everything is fine". I want to know that after 90K miles someone went in and did an analysis of engine wear and determined that mechancially there were no consiquences. Until then, I'll pop for the extra $2.50 per tank.

I understand that if someone drove a lot this can add up, and we all need to find ways to tighten our belts depending on our situation. I get that. But average driving in a TSX should be around 2-3 tanks per month. For me, there are other ways to save $7-10 / month besides risk my engine.

 

Why would u put lower grade fuel to save $200 or so a year. I avg 450 mile per tank with local driving and hwy.

 

Why? Because people are penny wise and pound foolish.

Why do people drive 5 miles to got gas for .05 a gallon cheaper? Do the math, assume 27 mpg, $4 a gallon, and 14 gallons for the fill...you saved $0.70 on the fill and spent $1.48 in gas to get to the cheaper station. The most economical choice is almost always fill at the cheapest station on your normal route...at about 25 mpg, a $0.01 reduction in price needs to be less than .425 of a mile off your route...

Also, mid-grade is a ripoff anywhere that premium is higher than 91 octane...unless it's priced right. In Texas, with 87-89-93 octane, the correct pricing would be 4.00/4.10/4/30...but they price at 4.00/4.15/4.30...meaning free money for the station. If you just have to use mid-grade when it isn't halfway between regular and premium, please just pump 8 gallons of regular and 4 gallons of premium in your tank...in the above example this mix gets you 89 octane for $49.20 vs. $49.80 using the mid-grade pump (or $0.05 cents a gallon).

The long term effect of running your engine with timing retarded by the anti-knock sensor from a major car repair study:

"Newer cars have a sensor that detects knocking. The sensor makes preventive adjustments when you use lower-ONR gasoline. But these adjustments come at the cost of power and acceleration.

In the long run, if you use regular gas when your owner's manual calls for premium, harmful engine deposits will accumulate. This will not only increase the likelihood of knocking, but also can increase emissions and reduce fuel economy...

In Summary
Although it's possible to use lower grade gas than recommended, the money you save now will disappear the moment your car has to go into the shop for engine repair or replacement. If you occasionally need to use lower grade gasoline because premium isn't available, don't fret, but don't make it a habit. If you want to keep your car running strong for many years to come, always follow the directions in your owner's manual and fill up with the recommended grade of gasoline."

 

I too remember someone told me about this. Since when did Honda put these black box recording devices in?

 

Honda started before 2000...check out the 12/27/2004 CSM link that showed 30 million vehicles tracking their drivers even then. Then the new link has more recent comments.

http://www.csmonitor.com/2004/1227/p13s01-wmgn.html

http://gooddaysacramento.cbslocal.co...dy-to-out-you/

 

Good info.

 

Thank you for that. So when you guys have engine issues. Dont think you warranty will cover them since they know what kind of gas is being ingested. I TOLD YOU guys!!! Honda is smart.

 

Ah, yes, this perennial topic. Always a great ice-breaker at the Acurazine cocktail party.

What Consumer Reports said (I have a subscription):
Ah, but here's Steve Mazor, principle auto engineer for the Auto Club of Southern California:
Yeah, it's CYA, but it's also practical advice. Don't "retard" your car's expected performance by switching from time to time. I would say do as Kathy does, use the same grade gasoline consistently. But....

I believe that Duck Dodgers (or maybe it was me?) did a cost comparison of getting say 27.5 mpg with 91 octane fuel, but getting 26.0 mpg with 87 octane ... I seem to recall that you ended up spending MORE at the pump as a result of buying more gas (given a certain yearly . Now, the drop in mileage, I'm the source, I did semi-scientific testing wherein I filled up at the same place directly on my normal daily drive route, drove roughly the same kind of driving (to work, to home, one shopping detour) between fill-ups. Same style of conservative driving pattern. I had a measurable drop in mileage (determined by dividing miles driven by gallons refilled, NOT the MID display from the ecu). It's been a while since I performed power-Excel user analysis, let me see if I can dust off those old skills to confirm this....

I think the assumption that you'll get more engine deposits using 87 octane versus 91 octane (or "regular" versus "premium") is outdated, all grades have the same sort of cleaning elements at a particular brand (mind you, Shell, Exxon, BP may add MORE to their fuel than, say, Easy-Peasy QwikStop). From Edmunds:

 

In that case-the warranty will not be honored for improper driving (racing it, etc) or not maintaining the engine properly-oil changes, etc. I know that those black boxes came in handy with the acceleration problems with Toyotas. Alot of times it was proven to be driver error. I recently had my tsx serviced at Stevenson Acura. They complimented me on how well maintained my car was and said it did not need anything.

 

Actually David, while the level of detergents is now even across most octanes in most brands, there is still something to the deposit issue. The retarded timing often causes a less complete combustion, causing more opportunities for deposits.

 

^ Really? Because I thought higher octane fuels had a higher resistance to combustion. If this is the case, wouldn't you theoretically have more deposits using 91 in an 87 car? Since the combustion temp in the 87 car would be lower than the 91 car, generally speaking.

 

Has anyone done some data logging with lower octane fuel - air to fuel ratio, knock count, etc?

Someone should get a kpro and dual ecu harness, tune for lower octane fuel and post the results!

 

Ah, yes. Duck 1, David 0.

Resistant to predetonation, not combustion. The K24 is a higher COMPRESSION engine, not hotter.


Okay, I don't recall if we did this before. In 2008, I started logging my mileage. In October 2008 and April 2009, I compared mileage over a full tank (less the reserve tank, which I measure to be about 14 gals: 17.1 gals - ~3.something gals reserve when the (E) light illuminates) of regular 87 octane fuel with premium 91 octane, using roughly the exact same "hyper-miling" driving style and similar workweek commute. Gas was bought from the same brand, station on my route. My records show a 2-3 mpg drop in both instances. Pardon the pun, your mileage may vary ... depending upon your driving style, and your regular driving route (city, highway, rush hour).

Now, the price differences between regular and premium gas varies from one seller to another. A couple on NPR's The Story related that some sellers may lose 1-2¢ on regular, but make up a little profit on premium, how much depends upon how much that seller makes up in convenience items, gross sales, etc. I've seen from 14¢ to 25¢ differences from one seller to another. Some hike each grade a set amount (e.g. 7¢, 12¢), others entice customers by reducing the jump from "plus" (89 octane here in NC) to "premium," e.g. "Oh, it's only 5¢ more for the super-unleaded, I'll just get that."

So I did a spreadsheet comparing the savings in using cheaper gas over 12,000 miles. The formula is yearly miles divided by measured miles per gallon, times the cost of the gas (MPG and cost are kept constant). As you can see, the wider the disparity in price, the more likely you'll be saving ... a little. But if you experience even a 1.5 MPG drop in fuel efficiency, you'd better be saving more than 25¢ per gallon, or you could end up paying more overall for the increased quantity of gas you buy. And the amount you save seems to come out to the cost of a single dinner out at a chain restaurant will cost you (subject to gradual increase if you drive 20,000 miles annually).[1]

The baseline is 28 MPG (about my average over 3 years), $4 a gallon. Priced marked in red exceed the baseline.



If someone sees a flaw with this, here's the Excel spreadsheet to mess around with on your own. I did this simply to calculate the values behind the "I'm saving money by using regular gas" hypothesis. Of course, if your fuel efficiency is unchanged, then you are saving money ... until you have to pay for any engine repairs.

[1] E.g. $4.009 -> $3.759, 28 MPG -> 26.5 MPG, total cost $1714 -> $1675. $39 annual savings,... BFD.

 

I put 91 in mine with the odd tank of 94 but I've recommended to my g/f's dad (owns a 2006) that he might as well put 89 in the tank and save a few bucks a tank. His driving style is plenty sedate and very, very rarely sees him on the other side of 3500 rpm so I don't think there's any harm in his case. For those of us who can't help gunning it I'd say 91 is the best bet.

Same horse, different course.

FWIW, I've noticed a couple cars where the ratings for the engine are provided for both regular and premium with the recommendation of premium. The Genesis Sedan V-8 comes to mind. I'd say that if it says "recommended" then that's what it means - it doesn't mean "required".

 

Supa...look at David's data...and my notes on station bullshit.

Regular or Mid-grade seems to reduce gas mileage...the savings may be illusionary.

Mid-grade is a cash cow for the station and a ripoff for the buyer.

 

Good presentation! Yes recommended and required are not the same thing, and the ECU can compensate for the lower octane fuel at the expense of both power and fuel economy! I'm glad someone put together a coherent explanation of the potential "false economy".

Why operate the car outside of its design parameters for a prolonged time just to save $39?

 

Ok so I started this thread. I decided to put regular in for one tank. I will never do that again. #1. I can tell a major difference in power. #2 City MPG went from 29 Average to 23. I know that 23 is still good but $4-6 more per tank for 29 is better plus I still will have the power. Hope this helps everone that is posting on this thread.

 

Stick to premium.. 93 Octane. the car will run great and last longer.

 

when we first owned our tsx we used premium gas (about 7,000 miles or more than one tank full). Let just say for me when we switched to regular we never went back to premium. We get over 30MPG. Use what works for you.

 

the way the car is driven-city or highway driving, maintenance also effects how long the car will last. My car is 4 1/2 years old, has the original brakes and has 122,000+ problem free miles. Yes it runs excellent using regular.

 

Nicely done.

So to summarize: doesn't save money, reduces power, forces engine to compensate, unknown long-term risk.

Seems like nothing left to discuss.

[/thread]

 

Don't you think your car would run better and get better mileage on 91? 30 mpg is good, but 35 is better.

 

note: I wrote OVER 30 MPG-If you were to drive my car without knowing what octane gas I was using you would not be able to tell. Last trip from NJ back to NC MPG was 35.8 (yes the old fashion way) I drove no more than 5MPH over the speed limit.

 

[quote=nj2pa2nc;12944297]note: I wrote over 30 mpg-if you were to drive my car without knowing what octane gas i was using you would not be able to tell. Last trip from nj back to nc mpg was 35.8 (yes the old fashion way) i drove no more than 5mph over the speed limit.[/quo


additional: USE WHAT WORKS FOR YOU!

 

My point is you'd almost definetely see a boost in fuel economy using what the car requires. It might be a little less noticeable since you presumably do a lot of highway driving, but I'm sure any alert driver would notice the difference between 87 and 91.

My .

 

Question is would it have been 38 with the right fuel.....

So the real point of David's analysis is that it's not what MPG your car gets, its the difference in MPG between the two fuels. Whether it's 18 vs. 20, or 35 vs. 37, the point remains the same - that higher mileage using the correct fuel may in fact be cost equivalent to cheaper gas and lower MPG.

 

You make a very good point. 87 doesn't completely have a complete combustion like 93 octane will in a motor with 11:1 compression. You're wasting fuel when using 87 because it doesn't completely burn off. I did a test on my TL with gas. 87 I got 27mpg going 75mph on freeway. With 93 my TL gets a consistent 34mpg. That means a 3.2L V6 is getting what your TSX almost gets. With a good brand fuel like Shell/Mobile one your car should see almost 40mpg with a light foot. 87 also over time would mess up the injectors so if you're getting that gas mileage now running 87, it wont for long.

 

How often do you get 38 MPG using the so-called right fuel

 

are you going by years or mileage. We owned a 91 Mazda MX-6 GT, bought new. When we sold it about 5 years ago for $5,000, it had the original turbo, engine, clutch, transmission and ran excellent. The new owner had to repaint it and fix the seats that were wore. It had over 250,000 miles and yes we used regular gas. (premium was recommended)

 

I'm amazed by this thread. You can afford to drive a luxury sports sedan, but you don't want to splurge a few extra bucks to fuel it with the Manufacturer's required fuel? Lets do the math: It's an average of an extra $.30 for premium compared to regular. So even if you let the 17 gallon tank drain until it was absolutely empty, you're looking at an extra $5.10 a tank. Less, (probably around $3-4) if you're like me and fill up before the light comes on. You're squabling over the price of a cheap Value Meal, a Starbucks, a Little Ceasars Pizza, to keep your high-priced Acura running properly? Don't be a cheapskate - It's all about proper and preventative maintenance! If you want to pay for regular, get a regular car. Premium cars need premium Fuel. Even then, with the higher octane, you'll see a noticeable increase in fuel economy, thus further canceling out the price difference.

 

Just wanted to step to play devil's advocate and also defend nj2pa2nc...it seems like people are piling on her right now, and I have read her posts on this subject for several years now, with interest. She is a great poster, willing to help others diagnose and solve problems with their cars.

I too use premium gas -- for my purposes. And this seems like a no-brainier to many of us, but it really depends on your needs, habits and purpose in driving your car.

I have the same car as nj2pa2nc does, (an 06 with 6 MT, with 37,000 miles), but with over 122,000 miles, she has driven her car 85,000 miles more. Clearly she drives a lot. If I drove as much as she does, I might rethink this subject.

With an additional cost of $.30 for premium, and 122,000 miles in 5 years, that's a significant savings for her... Using a 28 MPG city & highway avg., (which is higher than most people get), I figure she's saved between $1300-1500, or $250-300 a year.

She has stated she drives mainly on long commutes and trips, (and thus not trying to get every last ounce of HP), and if she's managing 34 MPG on the highway, with her car running flawlessly, what's the real downside for her? I see none. In fact, with her particular driving habits, I see her reasoning.

 

Boulder, I agree with you math, but disagree with the idea she is not running ANY risk. She is certainly more prone to deposits, and likely has a dirtier fuel system. I figure that because some brands of premium still have additional additives, and it's likely that a person would fill-up with one of those brands now and then.

That being said, if it's working for her, fine. It's just frustrating to see people buy a premium vehicle and then nickel and dime it to death.