Premium gas 91 or higher

[mdsegalo]

I tried a search and didnt see this addressed so I thought I would post. Sorry if this has been discussed. Has anyone dared to use 87 octane? I am getting to the point where the 91 is just too expensive. Will I do irepairable damage to my engine if I drop to the lower octaine? What is everyone else doing for increased gas mileage?

[Interceptor]

Our cars can handle the lower octane but you may see a loss in mpg. Plenty of users are using 87 and have reported no problems. I myself have stuck to using higher octane since I know for a fact my mpg have increased from 24 to around 27-30. If you really do the math you are only paying a few dollars more per fill up with the higher suggested octane. Just an opinion and there will be plenty.

[mdsegalo]

I guess I didnt realize that mpg was tied to it. It would be worth the extra $3 or $4 if you get increased mileage. I just do to much driving....

[jwrussell]

Kind of surprised nothing came up for you, there have been recent conversations aplenty on this topic. Consensus is you should be fine at 87, but as noted, you may lose out on mileage.

[dano1atty]

Or you could bump up to 89. Right? I asked this a few years ago, and we agreed that 89 was fine. I have never noticed any drop in MPG. Not that I was really checking. But jokes aside, I average about 27-28 in mixed driving. On one occasion, I reported getting in the high 30s, like 38, or something.

[Dex4]

I have used 87 and 89 for over a year in my 03 Arc 2.0T, I can feel a little hesitation when boosting (the computer probably senses a slight knock so it needs to retard the timing). My gas mileage was around 29-30. I now run 91 or 92 octane and mileage is about 32-33. Even though it costs $.20 per gallon, it ends up to be about the same in cost and the powerband is smoother.

[LaserRed9-3Aero]

Originally Posted by mdsegalo

I tried a search and didnt see this addressed so I thought I would post. Sorry if this has been discussed. Has anyone dared to use 87 octane? I am getting to the point where the 91 is just too expensive. Will I do irepairable damage to my engine if I drop to the lower octaine? What is everyone else doing for increased gas mileage?

Many (heated) discussions about this. Here and elsewhere.

All modern cars with knock sensors will (ok, SHOULD) run on 87 octane without damaging the engine. I am not an expert, but your 9-3 should be OK with it. Under heavy acceleration the engine management may retard the timing to prevent knocking. Your engine will produce less power but it shouldn't cause any damage. All octane measures is the resistance to pre-detonation (knock). Knock is what can damage the engine. The higher the octane, the harder it is for the gas to pre-ignite itself due to heat and pressure. Since we all have turbocharged engines, heat and pressure are two very real factors for us. High Octane = Advanced timing + high boost pressure => more/optimal power. Low Octane = retarded timing + lower boost pressure (maybe... I don't know for sure) => reduced power.

There are debates here and elsewhere as to whether or not the octane affects MPG. I think it depends on the car. As others have said, it appears that you'll get better MPG on the recommended octane than on the cheaper stuff. I haven't run anything other than 90-93 in my Aero, so I can't say for sure. I used to own a Subaru Impreza WRX and once had to run 87 octane in it because that's all the station had (backwoods). It was a terrible experience. The engine stumbled and it felt like the turbo was gone. Highway MPG suffered 2-3 mpg as well. Not amusing. Totally different car from the 9-3, of course, but from that one experience I don't feel the need to test 87 in my Aero.

In my neck of the woods, 93 is $.20-$.25/gallon more than 87. Doesn't seem to matter if gas is $1/gallon or $10/gallon. I paid for a high-performance sedan, and I intend to keep the maximum amount of performance on hand if/when I want it. The extra $2.xx/fillup difference between 87 and 93 is of no consequence to me.

To effectively save gas, alter your driving habits. Check the tires. Keep the car tuned up. Practice 'hypermilling' techniques of slow acceleration and lots of coasting with little brake usage. Drive under the speed limit. Optimize your errands. Carpool. Outside of that, there's really not much you can do other than sell the car and buy something with super-MPG ratings. Or ride a bike. Or walk!

[Ummagumma]

I usually drive on 91, yesterday filled up with 87 and I don't see any lack of performance or MPG reduction so far - in fact while going to work I hit over 30 mpg avg first time in 2 months I had this car.

I read and read and read on this subject and I think the consensus is, there's very little drop in power and MPG when using 87 vs 91 in a modern vehicle unless it was specifically designed for high octane (i.e. 91 is _required_ vs "recommended"). Depending on the driving habits, you may or may not feel this drop in power - I know I don't.

The other question is whether higher octane somehow burns "cleaner", again I found lots of conflicting opinions, it seems if there's really any difference it's again minimal.

OTOH, the difference in price between 87 and 91 isn't all that much, especially with gas near 4 bucks a gallon. I figured using 91 exclusively will cost me about $120 per year - not like it's going to break the bank.
So, it's a hundred dollars a year vs peace of mind and minimally better performance - in the end the choice is up to you and quite honestly it's not a life or death decision, either way.

[Interceptor]

$300 a month for me as far as I drive...Man not much else I can do except eat crow....

Quaaakkk!!!

[Krieg]

You got a Meijer out by you? They've got E85. It is generally about 50 cents cheaper than 87 octane gas.

I put in just enough E85, mixed with 87 octane gas, to get the octane to a little over 91. 4 or 5 gallons in the 16.4 gallon tank does the trick.

E85 has about 100 octane. The extra octane makes sure that there's no dropoff in performance like you'll see with straight 87 octane gas.

Ethanol does have less energy per liter than gas, so fuel economy is a little lower than with "real" 91 octane gas. But it is no worse than what people have reported with 87 octane. I've been averaging about 23.5 mpg at an average speed of about 28 mph.

I actually filled up just this morning. I checked the mileage right after I got off the highway on the way to work. It said I was at 29 mpg at an average speed of 45 mph. So highway mileage may very well be no worse than for 91 octane. I set the cruise at 65 mph.

I'm documenting my experience with E85 in my blog: www.drunkenswede.blogspot.com

[CMerriman]

Originally Posted by mdsegalo

I tried a search and didnt see this addressed so I thought I would post. Sorry if this has been discussed. Has anyone dared to use 87 octane? I am getting to the point where the 91 is just too expensive. Will I do irepairable damage to my engine if I drop to the lower octaine? What is everyone else doing for increased gas mileage?

Using a higher octane gas will get you better gas mileage, and only costs a couple extra dollars every fill up.

You would be foolish to put 87 in your car.

[JonV]

"and only costs a couple extra dollars every fill up." is something that someone says every week, well if gas went up 20 cents this week and you buy 30 gallons a week yeah that's only 6 bucks, but the week before that it went up 20 cents, and again the week before that etc so in three weeks the cost of 30 gallons rose 18 Dollars or 72 Dollars a month..now think about how over the last year or so the price has risen? To some people that's a substantial amount.

These cars will run on 87 but you won't get the best power/performance.

[LaserRed9-3Aero]

Originally Posted by JonV

"and only costs a couple extra dollars every fill up." is something that someone says every week, well if gas went up 20 cents this week and you buy 30 gallons a week yeah that's only 6 bucks, but the week before that it went up 20 cents, and again the week before that etc so in three weeks the cost of 30 gallons rose 18 Dollars or 72 Dollars a month..now think about how over the last year or so the price has risen? To some people that's a substantial amount.

These cars will run on 87 but you won't get the best power/performance.

The cost of gasoline isn't really the issue here. Not directly. It is getting more expensive every day, and that hurts all of us to some degree. I don't debate that fact at all. But it's the price difference between 87 and 90+ that matters to this discussion. Is that difference in price weighed against the 'consequences' worth it? That's the question.

Let's say you drive 1,000 miles a week. That would be a lot. 52k/year. Not out of the question, but really high for most of us, I'd bet. Let's pretend that regular-grade, 87 octane is $4/gallon. Therefore, premium-grade, 90+ octane is $4.20/gallon. Let's say you average 24mpg. You're then burning through 42 gallons of gas a week. Now look at the numbers. Assuming that there is no difference in fuel economy, and you fill up on 87 octane, you're spending $168/week. If you fill up on 90+ octane, you're spending $176/week. $8/week. Eight bucks. $8 out of $168+. That's $416/year difference if you're driving 52,000 miles a year. Since most of us drive far less, the total price difference will be less as well. For me personally, the difference between 87 and 93 is maybe $130/year. The performance & peace of mind is definitely worth that for me. Maybe it isn't for others.

The cost of gas is irrelevant to the discussion of 87 vs 90+, so long as the difference remains about $.20/gallon. And if you actually get 1-2mpg better on 90+, then the difference is even less and there are even fewer good reasons for using 87 octane instead of 90+ as recommended.

Of course, if 90+ starts to increase in price compared to 87, that would make a difference. If 87 was $5/gallon and 93 was $10/gallon, you can bet that I'd be one of the ones asking if it was ok to run 87.

[Krieg]

You make a good point regarding that static 20 cent cost difference.

My biggest problem with E85 is that Meijer prices it 50 cents less than 87, no matter what the price of 87 is. Is E85 a ripoff at $3.30 a gallon when 87 is $3.80 a gallon? Are they making money hand over fist? Who knows!

I know for a fact that there are times of the year that refiners "give away" octane. There are times when 87, 89, and 93 octane gas all have 93 octane. So that 20 cent differential is totally marketing and demand driven, not driven by the true cost of the fuel.

If it the same situation with E85? I wonder.

[JonV]

The OP said "I am getting to the point where the 91 is just too expensive."

Cost certainly is at least half the issue, it's why the thread was started.

If a guy can save 100 bucks a month and put it to good use or other needs and he's not looking for optimum performance and power 87 will work fine.

[LaserRed9-3Aero]

$3.30/gallon for E85, eh?

As of yesterday I noticed that one of our local stations was selling E85 for $2.83/gallon. Caught my attention because 93 was $3.83. It was $2.30ish/gallon when regular gas was $2.70ish. Its price seems to be increasing at a much slower pace than 'normal' gas.

While I'm not brave enough (or patient enough) to try the mixing as you are, it is enough to make me want my BioPower 9-1x.

Or just curse that the price of food is going through the roof....

Interesting note about the gas grades. I didn't know that. I guess you're paying the extra cost as a guarantee of the octane, and not a strict octane rating.

Originally Posted by Krieg

You make a good point regarding that static 20 cent cost difference.

My biggest problem with E85 is that Meijer prices it 50 cents less than 87, no matter what the price of 87 is. Is E85 a ripoff at $3.30 a gallon when 87 is $3.80 a gallon? Are they making money hand over fist? Who knows!

I know for a fact that there are times of the year that refiners "give away" octane. There are times when 87, 89, and 93 octane gas all have 93 octane. So that 20 cent differential is totally marketing and demand driven, not driven by the true cost of the fuel.

If it the same situation with E85? I wonder.

[jwrussell]

Originally Posted by JonV

The OP said "I am getting to the point where the 91 is just too expensive."

Cost certainly is at least half the issue, it's why the thread was started.

If a guy can save 100 bucks a month and put it to good use or other needs and he's not looking for optimum performance and power 87 will work fine.

Ummmm...exactly how many miles/month are you driving to think you can save $100/month between 91 and 87 Octane gas??? The price diff. between regular and Premium, just about everywhere, averages .20. We have what, ~16 gallon tanks in our 9-3s? Two tanks of gas/week would be $6.40 per week difference. That's $25.60/month. $307.20/year. At that difference you'd have to be filling up 8 times a week to be talking 100 bucks a month.

[Krieg]

While I'm not brave enough (or patient enough) to try the mixing as you are, it is enough to make me want my BioPower 9-1x.

Nah, doesn't take any bravery. I've got graphs over at the blog showing just what you're going to get when you mix. They show gallons of E85 on the X axis, and show octane and ethanol content on the Y.

I've found that you need to keep it right around 30% ethanol, which works out to about 5 gallons in a tank. Much more than that, and you can throw a CEL.

I've also documented that the EPA is investigating higher ethanol blends in non-flex fuel vehicles. They're looking at going from the current 10% ethanol to 15% or even 20%. The risk of mixing, say, E20 would be minimal, but then the cost savings would be minimal as well.

I choose to mix to E30 to maximize the cost savings. It is working pretty well so far. I'm through 6 tanks of the stuff. So far so good.

I'd kill to have Meijer selling E85 for under $3.00!

[Krieg]

Another idea is to sell the Saab and buy a used Taurus. On the blog I've got a list of E85 compatible vehicles with the VIN number to look for for E85 compatibility.

There are a ton of dirt cheap E85 compatible Taurus out there.

I know, I know, who wants to drive a Taurus, right? Hey, you're the guy that wants to save a buck!

[Adrock]

I've only had my 9-3 for a week, bought it from a non-Saab dealer (it was a trade in for a Subaru.) I have no idea what the dealer put in it when they delivered it to me. But I got 30+ on that tank. I'm getting 29.8 on my 2nd tank, which for ****s and giggles was 87, but I also realized with this tank that I bought a fairly well performing car so I might as well punch it a bit! Bear in mind, I drive 70+ miles a day at 70MPH average.

I do have a question, does outside ambient temp affect it? Or are intake air temperatures too hot with the turbo to be affected by ambient temps?