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Discussion Starter #1

After seeing this video, I don't know the whole hoopla for premium gas. Even if the manual says to use it. Even the VP of the fuel association was saying well.. I haven't see these studies that contradict.
 

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My 2103 Brabus recommends Premium, so that is what I run. My 2003 New Beetle Turbo S, the same so that is what I use. My 2015 Ford F-150 2.7 Ecoboost (twin turbo) recommends regular (which I find interesting since it has two turbos) so I run regular.
 

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87 vs 91/93 many discussions..............

And all agree that the smart WILL run on 87. But you get very low MPG,and make engine work harder. As a friend once
said,"it only costs a little more to go first-class"!!.......................
 

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A Benz mechanic at the dealership showed me a ruined W453 Smart motor with some 40K miles on it. Cracked rings from very tiny detonations within. He said running premium prevents this sort of thing, even with the knock sensor system.


A smart isn't a really expensive car, so why cheap out on the gas with what you are saving on payments?


S u b R o s a
 

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Wait wait, we're talking about numerous different generations here.

If you have a turbo smart (450, 453, or Euro spec 451) you should be using whatever the manual says to use. The engine needs that detonation resistance.

However if you have a naturally aspirated smart (US spec 451), I'd say there is no shame in running 87. Some people here have never used a drop of Premium, yet they're putting around with over 100k miles without issues.

I wouldn't recommend running 87 (I'm not going to spit in the faces of engineers who are smarter than I am) however I know it's hardly the death sentence it's made out to be in the naturally aspirated cars.

And I take the advice of a mechanic with a grain of salt. If I took my smart to each of the three area dealerships with the same issue, I'd be likely to get three different answers. And that's not me ragging on mechanics, that's exactly how it works in the IT world, too. I may say something isn't working because of x, but a colleague would say y.
 

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Makes a big difference how the motor was run. Oil changes, filters, driving conditions, load, etc. Hard to make a generalized statement that gas quality was the main contributing factor. I stick with premium as locally it is available without that darn ethanol. I get the best power, and miles per gallon so I stick with it.
 

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Driving conditions certainly matter, and my constant runs screaming my '09 Pure up and down steep grades in hot weather definitely required 91 or better. It would occasionally ping on 91 octane. Eventually it gave up at 210k miles and it was the pinging that caused its eventual demise.
 

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30 cents more a gallon for the premium over regular where I live, take 10 cents off per gallon with my Shell Card so it's 20 cents, I'll stick with the V-Power premium. Moving on now.
 

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The octane rating of gasoline is a rough measurement of how resistant it is to spark knocking. When the spark plug ignites the gas you want a nice even burn across the top of the piston. When the gas doesn't burn evenly it causes shock waves or vibrations if you will. These vibrations can cause engine damage. In hotter weather it spark knocks and even when it is so slight you cannot hear it (marbles in a can) the knock sensor on the side of the engine block detects it and sends a signal to the ECU. The ECU says "man I gotta stop this detonation" so it retards your ignition timing. Retarding the timing in turn decreases your power output of the engine.

If you have ever ran interstate on a 95 degree day with the air on and you hit a hill you can notice a difference between 87 octane and 93 if you know your car well and pay close attention. If you are in a cooler climate you may never notice, but be sure the engine computer is going to protect its engine as best it can.

The little Mitsubishi 3 cylinder engine on the back of your Fortwo is in the worst of conditions. It does not get really good air flow over the outside of the engine anyway. The heat does pool somewhat over the top of the engine in it's little cavity. There is no air flow when you are sitting still because the radiator and cooling fan are in the front. Hot days and engine load can be brutal.

Your little engine is smaller in size than a Harley Davidson motorcycle. It has 10 to 1 compression which is pretty high. Driving in auto mode causes the engine to be in the lower rpm range most of the time so coolant flow is slower at lower RPMS but the engine is pulling at a higher load due to a lower RPM. You are only circulating about a gallon of antifreeze to cool the engine. The Fortwo gets a bad rap for only being 70 horsepower, but that little engine is a workhorse and you can lug it down to 1500 RPM and it will pull as smooth as silk and never misfire.

Heat is your engines worst enemy with low octane fuel and it is hard to find good gas that isn't 10% ethanol made from corn. So while you are motivating down the road at 50 MPH in cool air conditioned comfort on a 85 to 90 degree day remember your little engine out back that is working it's butt of for your comfort. It gets good mileage and it isn't your typical car, but I think mine deserves care and good fuel. If you take care of it, it will take care of you. I say all of this because I ask a lot of my Smart. You might do fine on regular on not so hot temperatures but I'm not willing to find out the error of my ways by destroying my engine. I tore my engine down at 36,000 myself to replace burned valves and it is hard to do. Access is so awkward to get at the engine for anything that's why it is easy to neglect it checking oil, fluids etc,... So trust me I know what engine damage is, how costly replacement parts are and how hard the labor is to put it back together. I have been a car mechanic for over 40 years and have seen a lot. I know how to take care of a car because I fix ones everyday that people don't take care of properly.

I probably push my Smart more than most because I do a lot of towing in these steep West Virginia hills. I can fill Max up from bone dry to full for $23. For 8.5 gallons of gas it's not going to break the bank to fill it up with high test. You get great mileage anyway and even it didn't help, my peace of mind that I'm doing everything I can to protect my car is well worth it to me. When I'm on interstate with that car hauling trailer in the middle of a long hill and Max is pulling his heart out for me keeping me at 60 mph in air conditioned comfort, it's very much worth it. I can only speak for me. DCO





 

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The octane rating of gasoline is a rough measurement of how resistant it is to spark knocking. When the spark plug ignites the gas you want a nice even burn across the top of the piston. When the gas doesn't burn evenly it causes shock waves or vibrations if you will. These vibrations can cause engine damage. In hotter weather it spark knocks and even when it is so slight you cannot hear it (marbles in a can) the knock sensor on the side of the engine block detects it and sends a signal to the ECU. The ECU says "man I gotta stop this detonation" so it retards your ignition timing. Retarding the timing in turn decreases your power output of the engine.

If you have ever ran interstate on a 95 degree day with the air on and you hit a hill you can notice a difference between 87 octane and 93 if you know your car well and pay close attention. If you are in a cooler climate you may never notice, but be sure the engine computer is going to protect its engine as best it can.

The little Mitsubishi 3 cylinder engine on the back of your Fortwo is in the worst of conditions. It does not get really good air flow over the outside of the engine anyway. The heat does pool somewhat over the top of the engine in it's little cavity. There is no air flow when you are sitting still because the radiator and cooling fan are in the front. Hot days and engine load can be brutal.

Your little engine is smaller in size than a Harley Davidson motorcycle. It has 10 to 1 compression which is pretty high. Driving in auto mode causes the engine to be in the lower rpm range most of the time so coolant flow is slower at lower RPMS but the engine is pulling at a higher load due to a lower RPM. You are only circulating about a gallon of antifreeze to cool the engine. The Fortwo gets a bad rap for only being 70 horsepower, but that little engine is a workhorse and you can lug it down to 1500 RPM and it will pull as smooth as silk and never misfire.

Heat is your engines worst enemy with low octane fuel and it is hard to find good gas that isn't 10% ethanol made from corn. So while you are motivating down the road at 50 MPH in cool air conditioned comfort on a 85 to 90 degree day remember your little engine out back that is working it's butt of for your comfort. It gets good mileage and it isn't your typical car, but I think mine deserves care and good fuel. If you take care of it, it will take care of you. I say all of this because I ask a lot of my Smart. You might do fine on regular on not so hot temperatures but I'm not willing to find out the error of my ways by destroying my engine. I tore my engine down at 36,000 myself to replace burned valves and it is hard to do. Access is so awkward to get at the engine for anything that's why it is easy to neglect it checking oil, fluids etc,... So trust me I know what engine damage is, how costly replacement parts are and how hard the labor is to put it back together. I have been a car mechanic for over 40 years and have seen a lot. I know how to take care of a car because I fix ones everyday that people don't take care of properly.

I probably push my Smart more than most because I do a lot of towing in these steep West Virginia hills. I can fill Max up from bone dry to full for $23. For 8.5 gallons of gas it's not going to break the bank to fill it up with high test. You get great mileage anyway and even it didn't help, my peace of mind that I'm doing everything I can to protect my car is well worth it to me. When I'm on interstate with that car hauling trailer in the middle of a long hill and Max is pulling his heart out for me keeping me at 60 mph in air conditioned comfort, it's very much worth it. I can only speak for me. DCO





BRAVO!!!! :yelclap:

These car critics, magazines, etc, are really just looking for more readers, attention, click-throughs, etc, from people interested in learning. Yes, under certain circumstances, running 87 octane in a 91 octane vehicle may be just fine thanks to timing retardation/etc by ECU's. But when you car develops 270 hp and you're on a flat road in 70 degree weather you likely have no need to worry about 87 octane hurting the engine requiring 91. It just isn't a big deal to lose a few hp's because the driver likely won't notice and the engine isn't being challenged.

But the smart engine is tuned at max efficiency off 91 octane. Using 87 in it is shooting yourself in the foot because even on good weather days and non-challenging roads, the overwhelming majority of smart car owners will find themselves at least a few times a year in challenging conditions if not from the road traveled, the weather. At 999cc's and 70hp's, there really isn't much margin for error.

These car critics and journalists will not foot the bill when SHTF. I guarantee that. Your thorough explanation was badly needed on this forum. :nerd:
 

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The "what fuel should you use?" topic will be a horse continually bludgeoned to death for as long as ICE smarts exist. ;)

I also need to remind (namely our newer members) that using Premium doesn't guarantee that your engine will last. We've had folks come through with burned valves and they followed their manuals to the letter. In fact, that's how Marvel Mystery Oil became popularized in this community.

So whatever fuel you choose, at least make sure you keep up on the maintenance. :)
 

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If a vechile does not detonate on 89 octone why would it decrease engine life. That is an ignorant statement. I would suggest that we have better fuel here in the USA vs Europe. I have no proof but we are lots less money and refine it here.
 

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Discussion Starter #17
And all agree that the smart WILL run on 87. But you get very low MPG,and make engine work harder. As a friend once
said,"it only costs a little more to go first-class"!!.......................
Yea if it is first class then for sure I'm upgrading. However if its advertised as first class however is still Coach then I'm definitely not paying. I just started tracking my fuel usage, so after I get a baseline on premium gas I'm going to switch to regular to see if I get better mileage.
 

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If a vechile does not detonate on 89 octone why would it decrease engine life. That is an ignorant statement. I would suggest that we have better fuel here in the USA vs Europe. I have no proof but we are lots less money and refine it here.

You won't always know or hear it, especially if it happens while you're driving on a loud freeway and the pinging is competing with tire roar, wind shear, engine noise, and your stereo speakers. With this particular 999cc engine, it just isn't a good idea. I'm speaking from direct experience. Time and time again these engines show evidence of low octane combustion issues.
 

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I have seen pistons that the engine had denotation. Looked like a hammer had beaten them. But they also could hear it.That little engine is directly behind us and I should hear it if this happens. Now my 451 there was a noticeable difference in mpg and performance. Not so with the 453
 

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You can run whatever octane in your car you want. It's your car. If it blows up it's you that has to get it fixed. The reason we even have a forum here is to learn information from each other and take the advice or leave it. Arguing get's us no where. I said what I said because I truly care about my friends on this forum and we all here love the Smart brand for whatever reason.

Here's pics of my valves out of my Smart that I removed at 36,000 miles. It cost over $900 in parts and machining to fix it and I did the labor myself. That repair would cost twice that at a dealership, maybe a little less if you could even find an independent garage that could handle the repairs. Shim buckets have to be done carefully and exactly. So the proof is in the pics as to what happened to my Smart before I bought it. It was a shock to me. I was getting ready to have a 2nd hip replacement and I thought I was buying a low mileage Smart that I could drive for a few years with only maintenance. What I ended up with was a car I had to drop the engine and repair a month after a hip replacement. Even with valves this bad it did not run noticeably rough. It just started lighting the check engine light. P0303 code. The sensors on the engine are sensitive enough that it was picking up a misfire before even I noticed it. I can't say that it was low octane fuel caused this or a dirty air filter or lack of oil changes. But what I am saying I do not want to go through the head rebuild again for some time to come. So as a "precaution" I run high test, use Marvel Mystery oil. I do an oil change every 5,000 miles because I do a lot of towing. Not everyone that plays with a loaded gun gets shot and I hope that no one has to go through the ordeal of finding good parts which I had to get from the UK. As I said earlier "I can only speak for me". DCO



 
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