Regular Unleaded Question

[Vixen]

I'm sure this has been discussed but I did a quick search and didn't see anything..

Let's say that I know someone who's husband put regular fuel instead of premium in their ms3. That someone is a little upset and wants to know what long term effects using regular would cause. That someone needs good info to back her argument that premium is more efficient and better in the long run.
If you have any thoughts on the subject...please share.

Thanks!

[erik84]

You might get some knocking going on, and also loss of power. The MS3 engine is higher compression and is capable is making more power from the 91 octane. Where as the 87 octane engines won't show any power improvement when premium is put in. But I am unsure about what will happen after long term use of regular gas.

[wisniaPl]

I put 91 once ,and car had no power now Im only putting 93 for me its a very big difference in power....

[ProtoType5]

Boosted engines need premium dude...PREMIUM....

It's all to doo with "Pre-DETONATION"...which is common in the MSP, but I haven't heard of in the MS3...yet....The ECU is programmed for the fuel...it will run like crap and may "knock" under hard acceleration or higher rpms...This can throw a rod litterally through the block...

basically with boost more air + more gas = more power/more compression in the cylinders...when the cylinder compresses this air, the temperature skyrockets prior to the spark ignighting the fuel/air mix. Low octane fuel has the potential to detonate due to the compression only...before the spark is supposed to ignite the mix...this causes a disruption of the "cycle"...putting extreme stress on all pparts involved...

just tell him he's wrong...fill with premium or sell the Speed and get a regular 2.3L....and yes I like "quotes"....and long winded answers too...

[twowings]

If by "long term" you mean the effects of 1 tankful there's no cause for alarm...if you mean your significant other intends to use 87 octane from now on, then you need to open your Owner's Manual to "Recommended Fuel", scan the information into an image file, print it onto a t-shirt, hand it to him and say, "Here, nimrod, in case you FORGET AGAIN !"

(braindead)

[RENE063]

I have a regular 3 5-door. However, I got it by trading in a Camaro Z-28 which required premium fuel. One tank of 87 isn't going to kill anything. And as stated above, the engine is built and based on compression and detonation of the fuel which premium reacts properly to the specifications. Take it easy on accelerating on this tank of gas and get back to the premium.

Now for the economic side of things. Premium is usually .20 more expensive than regular. Our tanks hold what? - 15 gallons at most. 15x.20= $3.00. In the grand scheme of things, lay off the pack of cigarettes, don't eat at (any given fast food joint) at least one time each week, don't get the half mocha, half cap., 1/4 espresso creamed latte' and just get a normal cup of coffee. I could go on but why!? Just justify why $3.00 is not that big of a deal.

[Mid_Life_Crisis]

I once read a description by some famous automotive guy (I've long since forgotten who) of pre-ignition. He basically said that you might as well just take the cylinder head off and beat the pistons with a hammer.
If for whatever reason you ever end up with low grade (quality or octane) in a car designed for high octane, go very easy on the throttle until you are down to half a tank and then top it off with the best stuff you can find.
Tell your husband the recommended octane is cheaper than rebuilding the motor annually.

[desperado-c]

You might get some knocking going on, and also loss of power. The MS3 engine is higher compression and is capable is making more power from the 91 octane. Where as the 87 octane engines won't show any power improvement when premium is put in. But I am unsure about what will happen after long term use of regular gas.

I don't think the hubby cares about the power, he's thinking only about economy. But this is interesting write-up. The ECU can only compensate for so much and some of the nastiness described here seems likely to occur with long-term use of low-test:

http://www.bimmerforums.co.uk/thread99.html

You have to take control and hide the keys from him or use whatever tools you have at your disposal to put this to a stop. If that doesn't work, tell him you need a boost gauge so you can greatly increase your gas mileage by staying off boost.

[Adammazda06]

go put a few gallons of racing fuel in to boost the octane.

[Kobyoshi]

I'm sure this has been discussed but I did a quick search and didn't see anything..

Let's say that I know someone who's husband put regular fuel instead of premium in their ms3. That someone is a little upset and wants to know what long term effects using regular would cause. That someone needs good info to back her argument that premium is more efficient and better in the long run.
If you have any thoughts on the subject...please share.

Thanks!

This 'someone' needs to severely scold their husband because lower octane fuel causes "knocking" which is just a nice way of saying 'detonation' which is just a nice way of saying 'beat the piss out of an engine'.

The octane of a fuel is it's resistance to 'detonation', the higher octane number the better, as 'detonation' subjects the head gasket, piston, rings, spark plug and other internals to severe stress and increased pressures.

Most automobiles have knock sensors installed nowadays which sense the harmonic shock waves created by 'knocking' and then temporarily retard the ignition timing in an effort to cease the 'detonation'... so one tank you should be fine, but I would tell this someone not to make low octane a habit to save a couple bones.

There many reasons gas powered aircraft use 100LL...

[tripledigits]

I don't think the hubby cares about the power, he's thinking only about economy. But this is interesting write-up. The ECU can only compensate for so much and some of the nastiness described here seems likely to occur with long-term use of low-test:

http://www.bimmerforums.co.uk/thread99.html

You have to take control and hide the keys from him or use whatever tools you have at your disposal to put this to a stop. If that doesn't work, tell him you need a boost gauge so you can greatly increase your gas mileage by staying off boost.

Great article! Most people don't realize that premium fuel has a slower burn rate than regular - which is exactly what higher compression and force fed engines need.

[Bravnik]

One tank full will do no real harm.

Have him read the owners manual and if that does not convence him, show him the little sticker on the gas tank door.

If all that does not work, then file for divorce as you have made a huge mistake and married the town idiot.

[Sacrilicious]

easy solution: don't let him drive your car. our car needs 91+ octane or we don't get to boost properly (due to pre-detonation as mentioned)...simple as that...=d

[shane02pro5]

Nicely put!!

You can put some "104 octane boost" in there and it should help as long as there's at least a 1/2 tank or more to allow it to mix up.


One tank full will do no real harm.

Have him read the owners manual and if that does not convence him, show him the little sticker on the gas tank door.

If all that does not work, then file for divorce as you have made a huge mistake and married the town idiot.

[Vixen]

Thanks for the info!

He's been banned from driving the car. Permanently.

[X4-SRT]

I put 91 once ,and car had no power now Im only putting 93 for me its a very big difference in power....

Lucky you. 91 is as good as it gets here in Las Vegas. :(

[MS3077]

Lucky you. 91 is as good as it gets here in Las Vegas. :(


lol! That must suck ballz. Sorry to hear this dude; your probably losing at least 100hp

[X4-SRT]

lol! That must suck ballz. Sorry to hear this dude; your probably losing at least 100hp

I do! It's cool though because I get the power back with all my powered by honda, and nos stickers.

[MS3077]

I do! It's cool though because I get the power back with all my powered by honda, and nos stickers.

(lol2)

[dkswim]

slap your hubby up side the head call him names and what not dont let him forget the time he almost blew up the car by putting the wrong gas in it. in all reality as long as your not putting a load on the car its alright to run lower octane i would not but thats beacuse i like to get into boost regurly. and its only 3-4 dollers more a tankfull. you might notice car runs like poo for the next 3 tankfulls beacuse the car pulled timing to compensate for the lower octane and car is sometimes reluctent to add it back. 100 low lead is funny it contains more lead then auto gas in the 70 did. i guess its all relative.

[Vixen]

slap your hubby up side the head call him names and what not dont let him forget the time he almost blew up the car by putting the wrong gas in it. in all reality as long as your not putting a load on the car its alright to run lower octane i would not but thats beacuse i like to get into boost regurly. and its only 3-4 dollers more a tankfull. you might notice car runs like poo for the next 3 tankfulls beacuse the car pulled timing to compensate for the lower octane and car is sometimes reluctent to add it back. 100 low lead is funny it contains more lead then auto gas in the 70 did. i guess its all relative.

I know it's not going to blow up my car. I'm not one of those dramatic types. I was just really pissed because I noticed the performance sucked balls. That's when I confronted him about it because I knew something wasn't right and he had been driving the car.
When I drive my car I want to rip up the road. I guess I'm just spoiled...LOL.

[happy and angry]

The owner's manual instructs you to use premium for a reason. Performance and fuel economy will suffer on lower octane fuel, and you run the risk of detonation and damaging your motor. If you screw up your motor on regular unleaded, it'll be immediately obvious to Mazda, and you'll probably void your warranty as a result.

Your husband needs to smarten up and listen to you, and it's sort of a shame you want/need the help of a forum to get him to listen to you about your own car.

[Bravnik]

I know it's not going to blow up my car. I'm not one of those dramatic types. I was just really pissed because I noticed the performance sucked balls. That's when I confronted him about it because I knew something wasn't right and he had been driving the car.
When I drive my car I want to rip up the road. I guess I'm just spoiled...LOL.


Sound like my kind of girl. Divorce him and I will divorce my wife and we can rip up the road together!!! (drive2)

All fun aside, my wife would clean me out and probably take the car as well. Oh well......dreams :)

[Vixen]

The owner's manual instructs you to use premium for a reason. Performance and fuel economy will suffer on lower octane fuel, and you run the risk of detonation and damaging your motor. If you screw up your motor on regular unleaded, it'll be immediately obvious to Mazda, and you'll probably void your warranty as a result.

Your husband needs to smarten up and listen to you, and it's sort of a shame you want/need the help of a forum to get him to listen to you about your own car.

I see your point but I've seen other people seek help for more trivial issues in the past. I just needed more ammo to back up the knowledge I already have.
Trust me I wish life was easy but I don't really want to be married to a "yes dear" type either.
Arguments happen all the time in every relationship and it's quite normal for married people not to listen to one another. I should know, it's been 13 years.

[Vixen]

Sound like my kind of girl. Divorce him and I will divorce my wife and we can rip up the road together!!! (drive2)

All fun aside, my wife would clean me out and probably take the car as well. Oh well......dreams :)

You're probably right. Women are vicious.

[Mid_Life_Crisis]

I noticed the performance sucked balls...


Edit:
Was going to say something really smartass but changed my mind...

[Vixen]

Edit:
Was going to say something really smartass but changed my mind...

What made you change your mind? Did you decide you were too much of a perv? :)

[Kynetx]

Don't worry about it. The car will sense the crappy gas and retard ignition timing to compensate. Nothing bad will happen except for gutlessness.

[samc86]

funny, there was a thread a while back about how rich the speed3 runs, that 87 octane actually didn't cause knock and actually increased fuel economy (the extra fuel actually cools things down and helps prevent detonation), i tried a tank, and sure enough economy went up, and i didn't notice any performance issues. so now i usually run regular.
no dyno runs, and no data logging to show knock counts, sorry. maybe someone with a dashawk or other logger wants to give a few gallons a try and let us know?

and i am familiar with the damage detonation can do. i was running my corvette without the knock sensor (too many false knocks causing too much timing to be pulled), and at the track a few times when it got hot and started knocking i didn;t let up like i should have. i now have a $700 set of forged piston paperweights. the top ring lands are just eaten away.