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  #1  
Old 07-30-2016, 02:41 AM
marines122181 marines122181 is offline
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Fuel

Hi all!

New Bimmer owner and very excited about it!

2006 330Xi - 115k miles

My question is regarding gasoline. I understand that it is recommended to use 91+. How important is that? Have any of you more experienced owners had any issues using 87 or 89? Thanks a lot in advance!
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  #2  
Old 07-30-2016, 05:40 AM
qiu qiu is offline
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Fuel

Have not finished my first tank of gasoline planning to add 93 from Costco, the lowest BMW suggests is 89 from my x3 manual
Check this link for more fuel details
http://www.edmunds.com/fuel-economy/...g-premium.html

Last edited by qiu; 07-30-2016 at 10:09 AM.
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  #3  
Old 07-30-2016, 07:52 AM
marcozandrini marcozandrini is offline
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Buy gas from a dealer listed in www.toptiergas.com. Why? BMW and other manufacturers got together and determined how well gas needs to clean the injectors and the back side of the valves. 91 octane is recommended, but you can use 89 octane without issue. The engine computer (ECU) determines when to retard the ignition. As a result you'll experience some reduction in performance in some conditions when using 89 octane.
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  #4  
Old 07-31-2016, 10:56 AM
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Tom K. Tom K. is offline
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Your 330i is a non turbo and will run fine on 87 octane, although peak power and fuel mileage might suffer slightly.

My 328i is tuned for 91 octane, but since 87 is acceptable, I generally alternate tanks of 93 & 87. I've been buying primarily from local off brand stations (heavier traffic = fresher gas) for 5 different Bimmers for 20 years with absolutely no problems, other than a heavier wallet.

Tom
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  #5  
Old 07-31-2016, 11:02 AM
marines122181 marines122181 is offline
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Thanks all. I appreciate the feedback. Knowing it's ok, I'm going to run a tank on 87 and then one on 93. I use a fuel tracker app so I'll see the difference in mpgs between the two and see the loss/gain of mpgs vs the price difference and decide which to use after that.

Thanks again
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  #6  
Old 07-31-2016, 08:33 PM
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Dave 20T Dave 20T is offline
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My criteria, in order of importance, is:

1. Use gas, never diesel, if your car is a gasoline car.
2. Use at least the minimum octane according to the owners manual. For some BMW's it's 87, 89 for mine, 91 for others.
3. Buy gas from a station that seems reliable in terms of gas not being too old, no water in the tanks (if you can guess)
4. Buy gas of a reputable brand. AAA recently tested gas and wrote that Top Tier brands did have less engine deposits. On the other hand, Top Tier gas is required to have 8-10% ethanol but it is increasingly very hard to find gas without ethanol.
5. Buy premium gas, 91-93 octane. You will get better gas mileage but maybe 0.2-1 mpg at most. The EPA tested cars and found that to be true but politically incorrect. Uncertain is whether 93 offers any advantage to 91. If not and you live in an area with 93, you could be economical and buy 3/4 93 and 1/4 87, which comes out to be roughly 91.

I don't alternate octane because when you put 87 in, it may knock until the sensor detunes the car. I just use 92, which is close to 91. There is no 93 here. There is 94 in Canada, at a much higher price and a quarter tank of gas away so not worth it.

Last edited by Dave 20T; 07-31-2016 at 08:35 PM.
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  #7  
Old 07-31-2016, 08:38 PM
marines122181 marines122181 is offline
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1. Duh?
2. My cap says 91. Book says 87.
3. I use a Sheetz that is right off a major highway. They get delivered to daily.
4. I'll have to look.
5. My current test will determine if the 0.2-1 mgp gain outweighs the cost difference. I'm not expecting it to.
5a. Good point. I'll stick with one or the other.

Thanks for the input!
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  #8  
Old 08-15-2016, 10:56 PM
marines122181 marines122181 is offline
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Finally have enough data(fill-ups) to provide this data.

3 tanks of 89:
Average 293 miles
Average 13.09 gallons
Average 22.38mpg

3 tanks of 93:
Average 361 miles
Average 14.515 gallons
Average 24.87mpg

87:
300 miles 22.38mpg = 13.4g
13.4g $1.94 = $25.966

93:
300 miles 24.87mpg = 12.06g
12.06g $2.44 = $29.67

Conclusion
93 would cost me approximately $4 more than 89 per 300 miles.

Being that this cost difference is so miniscule, do you think there is a benefit to engine component health in using 93?
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  #9  
Old 08-15-2016, 11:10 PM
jaybeee jaybeee is offline
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I would use the highest the factory recommends, I find this information on the gas cap. Your vehicle will detect whether it is 87 or 91 or whatever octane and adjust accordingly.

Personally since your vehicle says 91 on the cap I would think 93 octane would be a waste. I think it would be a waste of a BMW if you used 87 octane.
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  #10  
Old 08-15-2016, 11:16 PM
marines122181 marines122181 is offline
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The options near me are 87, 89 and 93. Hence the use of 93.
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  #11  
Old 08-15-2016, 11:23 PM
jaybeee jaybeee is offline
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Very well if 91 is not an option I would highly recommend 93. The car is designed to use 91 so 93 won't hurt but under 91 is not a good idea. I could talk your ear off about long term problems but it is all hypothetical. Basically if you run inferior gasoline you might need a long list of things like new spark plugs and that is a couple hundred dollar job to do yourself with the proper parts. BMW's are actually fairly environmentally friendly and using the proper gasoline contributes to BMW's having not a drastic environmental footprint.

Using 91 or 93 octane on a car that has 87 on the gas cap is an absolute waste of money.

P.S. I am from Canada, all my BMW's have had 91+ on gas cap. Regulations about measuring gas may be different in the USA and cars may be different specs. In Ontario we get 87,89,91 everywhere and maybe 94 at limited locations.

Last edited by jaybeee; 08-15-2016 at 11:30 PM.
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  #12  
Old 08-16-2016, 04:44 AM
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Doug Huffman Doug Huffman is offline
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One of the pros of Variable Valve Lift is reduced dependence on octane.
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Post hoc ergo propter hoc is a weak logic akin to arguing from ignorance, "I don't know, but ..." Better to be silent and thought a fool than to babble and remove all doubt.
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  #13  
Old 08-16-2016, 05:25 AM
Autoputzer Autoputzer is offline
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Quote:
Originally Posted by marines122181 View Post
Finally have enough data(fill-ups) to provide this data.

3 tanks of 89:
Average 293 miles
Average 13.09 gallons
Average 22.38mpg

3 tanks of 93:
Average 361 miles
Average 14.515 gallons
Average 24.87mpg

87:
300 miles 22.38mpg = 13.4g
13.4g $1.94 = $25.966

93:
300 miles 24.87mpg = 12.06g
12.06g $2.44 = $29.67

Conclusion
93 would cost me approximately $4 more than 89 per 300 miles.

Being that this cost difference is so miniscule, do you think there is a benefit to engine component health in using 93?
Modern cars de-tune themselves when inaudible pinging is detected. So, by running your car with sub-standard gas, you're forcing the car to de-tune. That could increase the carbon build-up in the combustion chamber over the long term. Severe pinging could actually damage the engine, but you'd hear it first.

You can make your own 91 AKI by mixing 1/2 89 AKI and 1/2 93 AKI, or 1/3 87 AKI and 2/3 93 AKI. The 87-93 AKI blend is usually the cheaper combination. They don't make 89 AKI gasoline. It's blended at the tank farm from 87 AKI and 93 AKI. The AKI is a weighted average of the blends. By tracking your MPG with the on-board computer (resetting the MPG when you fill up) you can accurately predict how much gas you will need before filling up the car.

Ethanol only has 2/3 the energy (latent heat of combustion) of pure gasoline. So, E10 (10% ethanol) only has about 97% the energy of pure gasoline, resulting in only 97% the MPG of pure gasoline. E10 is mandatory in the US, supposedly to reduce emissions during cold start-up and with older cars without O2 sensors, and to reduce our dependence on foreign oil. But, it's really just to pay back the "corn lobby" for their generous campaign contributions. The corn lobby is trying to up the mix to 15%.

Field testing (like you've done) has a lot of unknown variables (AC use, traffic, tire pressure, etc., etc., etc.). But, if you got the same results with 91 and 93, then paying for 93 would be a waste of money and not improve performance significantly. Use 93 AKI on track days, though.

Oh, an vacuum out your floor. That sand there is driving me nuts. I can't look it at.

Last edited by Autoputzer; 08-16-2016 at 05:31 AM.
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  #14  
Old 08-16-2016, 06:01 AM
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need4speed need4speed is offline
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Quote:
Originally Posted by marines122181 View Post
finally have enough data(fill-ups) to provide this data.

3 tanks of 89:
Average 293 miles
average 13.09 gallons
average 22.38mpg

3 tanks of 93:
Average 361 miles
average 14.515 gallons
average 24.87mpg

87:
300 miles 22.38mpg = 13.4g
13.4g $1.94 = $25.966

93:
300 miles 24.87mpg = 12.06g
12.06g $2.44 = $29.67

conclusion
93 would cost me approximately $4 more than 89 per 300 miles.

Being that this cost difference is so miniscule, do you think there is a benefit to engine component health in using 93?
+1
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  #15  
Old 08-16-2016, 09:33 AM
marines122181 marines122181 is offline
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Autoputzer,
Thanks for the informative reply.
Also, it's not "sand" but where the carpet has worn. The car was at the shop and just detailed when I took the pictures. Feel free to buy me a new carpet if it bothers you that much!
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  #16  
Old 08-16-2016, 11:54 AM
Autoputzer Autoputzer is offline
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Quote:
Originally Posted by marines122181 View Post
Autoputzer,
Thanks for the informative reply.
Also, it's not "sand" but where the carpet has worn. The car was at the shop and just detailed when I took the pictures. Feel free to buy me a new carpet if it bothers you that much!
I'll just resist the urge to click on the picture.

BMW carpet and floor mats are not known for durability. I bought two spare sets of floor mats when I bought my 535i. I alternate using the back mats to protect the driver's floor mat. You got me all freaked out now, though. I'm going to now have to watch my carpet, not just the mats.
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  #17  
Old 08-16-2016, 11:56 AM
marines122181 marines122181 is offline
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Oh I completely agree. Granted, the car is 10 years old, but I still don't interested so much wear UNDER the floor mat.

I've since picked up some custom sized floor mats for added protection.
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  #18  
Old 08-16-2016, 12:20 PM
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Dave 20T Dave 20T is offline
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Quote:
Originally Posted by Autoputzer View Post

BMW carpet and floor mats are not known for durability. .
I agree. I noticed a tiny amount wear on the thin floor mats after just a few days of use during European delivery so I immediately replaced the mats with aftermarket carpet mats in the summer and rubber mats in the winter.


Quote:
Originally Posted by Autoputzer View Post
You can make your own 91 AKI by mixing 1/2 89 AKI and 1/2 93 AKI, or 1/3 87 AKI and 2/3 93 AKI. The 87-93 AKI blend is usually the cheaper combination. They don't make 89 AKI gasoline. It's blended at the tank farm from 87 AKI and 93 AKI. The AKI is a weighted average of the blends. By tracking your MPG with the on-board computer (resetting the MPG when you fill up) you can accurately predict how much gas you will need before filling up the car.
A long unanswered question is whether US BMW's are tuned so that the optimal octane is 91 or whether that is a politically motivated statement to make owners happy in areas that 91 is the highest octane sold.

If 91 is the optimal octane, I was thinking of pumping 2 gallons of 87 for each tankful which would lower the octane to about 91. If you have 92 octane, then it might be 4-5 gallons of 87 depending on how empty the tank was.
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  #19  
Old 08-16-2016, 12:39 PM
coolrockdaddy coolrockdaddy is offline
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at $ 2.59/gal just use Shell 93 octane and drive !!!
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  #20  
Old 08-16-2016, 01:31 PM
Autoputzer Autoputzer is offline
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AKI (final) = [ AKI (old gas) x gallons (old gas) + AKI (new gas1) x gallons (new gas 1) + AKI (new gas 2) x gallons (new gas 2) ] / [ gallons (old gas) + gallons (new gas 1) + gallons (new gas 2) ]

If your goal is to repeat the AKI of the old gas, e.g. 91 AKI, the (old gas) components drop out of the equation. Also, the less old gas still in the tank, the less it affects the final AKI after fill-up. I wait until I only have about 1.5 gallons in a 18.5 gallon tank before refilling. I calculate how many gallons I need (trip odometer miles since the last fill-up / MPG since the last fill-up), divide by three, and put that many gallons of 87 AKI in. Then, I finish up with 93 AKI.

Where I live, 93 AKI is $0.55/gallon more than 87 AKI. Between my two cars, both requiring 91 AKI, I burn about two gallons / day. By blending to make 91 AKI, I save about $135/year.

Since 91 AKI is the highest AKI readily available in California and a lot of high-altitude areas, BMW tunes their "50 state" cars to get by on it. I generally drive my 535i gently to get better fuel economy (one reason I didn't get an M5), so 93 AKI likely wouldn't benefit me. I flog my other car on 91 AKI and never hear pinging. I used to very occasionally hear pinging on my E46 M3 when the engine was lugging down (e.g. going up a grade at 55 MPH in 6th gear, in the summer, with the AC on). If I'd downshift, it'd go away.

Frau Putzer's 130k mile Honda Accord is just now showing wear on the driver's floor mat. My Cobalt's wore all the way through before I even noticed. I always buy at least one set of spare OEM mats when I buy a new car. If I don't use them, the next owner gladly buys them for what I paid for them. I might lose ten years of interest, but it pays for peace of mind.

Last edited by Autoputzer; 08-16-2016 at 01:33 PM.
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  #21  
Old 08-16-2016, 02:39 PM
marines122181 marines122181 is offline
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I drove my 3 tanks of 87 for approx 1k miles. 95% highway at 75mph. Didn't hear or feel any complications or "noticeable" loss of power. I am quite surprised at the accuracy of the on board mpg estimate. Only .2 off on 93 and dead on with the 87!

You had mentioned field testing having variables. Yes, of course. I did take this into account. My route to/from work is the same and I use cruise the entire way sans 3 miles of town traffic. A/c was on auto each way. No excessive idling. Not perfect but as close to it as I could get.
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  #22  
Old 08-16-2016, 02:41 PM
marines122181 marines122181 is offline
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Just fyi, I'm simply going to use the 93. For a $4 week difference, it's not, to me, worth the hassle of figuring out extra numbers and creating 2 transactions per fill up by splitting the 93 and 89.
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  #23  
Old 08-16-2016, 05:08 PM
Autoputzer Autoputzer is offline
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Quote:
Originally Posted by marines122181 View Post
Just fyi, I'm simply going to use the 93. For a $4 week difference, it's not, to me, worth the hassle of figuring out extra numbers and creating 2 transactions per fill up by splitting the 93 and 89.
I don't pull the ticket out of the pump until I finish the second pumping. That way it's all on one ticket. I later record the transaction on my spreadsheet. I just have to use an "=" and a "+" when entering the values for gallons and cost in the spreadsheet.

I suspect the car's computer is more accurate than gas pumps. From keeping records, I've found gas pumps that are ripping me off, and some that are giving away free gas. Since new, the MPG from the OBC and the pump MPG from my spreadsheet are within one percent, but a lot of that is from me finding and going back to generous gas pumps.

Yeah, I'm a geek. The only odd ball app I have on my smart phone is a HP-42S emulator. The HP-42S was the geek's pocket calculator of choice back in the 1980's, and is considered the pinnacle of pocket calculator design. They're actually appreciating in value as collector's items, sort of the E30 M3 of calculators.
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  #24  
Old 08-16-2016, 05:31 PM
marines122181 marines122181 is offline
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Ok. That's a good idea. I'm usually putting in 14g so I'll try 7/7 on one transaction. Thanks for the idea.....geek.
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  #25  
Old 08-16-2016, 07:49 PM
Autoputzer Autoputzer is offline
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Originally Posted by marines122181 View Post
Ok. That's a good idea. I'm usually putting in 14g so I'll try 7/7 on one transaction. Thanks for the idea.....geek.
Let us know how 91 vs. 93's MPG's compare.

A lot of the performance chips end up making the car want 93 AKI or better. So, there's is some de-tuning in OEM to tolerate 91 AKI.
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