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USA: 89 Gas Ok to Use?

7K views 56 replies 31 participants last post by  SergioK 
#1 ·
In the manual, it says you can use 89 gas minimum. Just wondering if that really is ok and if it will affect the car in any way? Thanks.
 
#7 ·
No, although it can result in less performance, as the engine might retard timing, etc, to prevent knocking with the lower end fuel.

Your BMW has a high compression engine that is designed for high performance fuel. Putting low end fuel in to save a few pennies is foolish.
 
#12 ·
No. Your car will explode. :bigpimp:

Kidding. Of course. The car won't develop the power it was designed to deliver; if that is of no importance to you, go right ahead.

But I might suggest you calculate, with your average MPG and mileage driven per year, what the net savings is for you. This amount might be an acceptable value for the driving enjoyment it brings.

Or you could of course sell the car and buy a Camry; which if I am not mistaken uses Regular gas. :p
 
#15 ·
91 Octane



Use 91 ! Why restrict your Bimmer ? You bough a BMW not an Avalon. You might as well keep it in Eco Pro too. Enjoy your Bimmer, don't take the Fun out of Driving:thumbup::bigpimp: We have had BMW 3 Series since 2006, and we have never put in lower than 91. This question comes up every 6 months .
 
#23 ·
Ok, I tried to write some brief commentary here to have some critical thinking done. It didn't happen. Here's some thoughts for the OP:

Your car is tuned to handle 89 octane just fine. True power loss occurs when an octane is so low that knock events start to happen and the engine retards timing to prevent knock.

However, your car is meant to run just fine on 89 octane. You might lose 5 horsepower, about the equivalent of your engine going from sealevel to 1000 feet altitude. Yes, even in a turbo car - the power loss is still substantial from altitude, just not nearly as substantial as an N/A car.

Now, on the flip side, if you followed the logic of the posters on here, you do not GAIN lots of horsepower as your octane increases. It's not like at 93 horsepower you get another 10 HP, and then if you add octane booster you get 25 HP. OEM tuning doesn't work like that. When they say 89 is the minimum, they mean your engine is tuned to run just fine on 89.

...

Now, let's deal with fuel economy. Your car has to pull enough timing to make your fuel economy notably worse. I can accurately represent to you that not a single person on this thread who has posted knows whether or not the n20 pulls enough timing to reduce your fuel economy enough that it's a wash. In other words - no one who has posted actually knows one way or another. They are just spouting "play it safe" mantras.

However, if BMW has said 89 is a minimum octane, and they happen to have been the ones who tuned the engine and understand it's timing curve vs. octane requirements, you can imply they are saying "it's a wash" or "it doesn't matter."

...

Bottom line takeaways:

1. It won't hurt your engine
2. The performance it takes away will most likely be imperceptible. If you can't notice when there's a 75 pound kid in your backseat, you won't notice a 5hp loss.
3. The fuel economy won't be worse, may be equivalent, and may be the same

I see no reason you should be running 89 octane, but if that's all you have available, or you just want to try it out, go for it!
 
#24 ·
I appreciate your comments. Your last sentence should be in the revise though, shouldn't it? You should be saying, based on your comments, that running on 89 compared to 93 won't really make any difference. So wouldn't you be for using 89 vs. 93 if you can't tell (if you can't tell when you put a kid in the back)? Thanks.
 
#27 ·
No, my last statement is right in line. My point was that you can run 89 if you want, but there's no reason to unless you:

A. want too
B. don't have higher available to you

There's no harm in it, and you probably can't tell a difference, and maybe it'll save you a few cents. So if you OPT to use it, go for it.
 
#32 ·
Why would you use 89 when in the manual it says if you use the min octane rating you may hear KNOCKING!! Meaning if you have no option then use 89 but dont keep using it.


 
#33 ·
91 Octane

why would you use 89 when in the manual it says if you use the min octane rating you may hear knocking!! Meaning if you have no option then use 89 but dont keep using it.


+ 1
 
#34 · (Edited)
The average price per gallon for 89 octane in the area where I live in Los Angeles is around $4.29. That's for Top Tier gas like Shell, Chevron, 76, etc. The average price for 91 is ten cents more, $4.39. Assuming that you get around ten gallons each time you fill the tank, that means you're paying about $43.00 for 89 and $44.00 for 91, about one dollar less.

Actually, you can save even more money by buying inferior brands of gasoline using their 89 octane. Doing that, you save even more per tankful. Why anyone would want to save around two to three dollars every time they fill the tank by using a lower grade of inferior gasoline on a car like a BMW is beyond me. :(

If you want to use the gas that BMW recommends for optimal performance, then spend a little more money on 91 octane Top Tier gas and get the best. To me, that's a no-brainer.
 
#35 ·
The average price per gallon for 89 octane in the area where I live in Los Angeles is around $4.29. That's for Top Tier gas like Shell, Chevron, 76, etc. The average price for 91 is ten cents more, $4.39. Assuming that you get around ten gallons each time you fill the tank, that means you're paying about $43.00 for 89 and $44.00 for 91, about one dollar less.

Actually, you can save even more money by buying inferior brands of gasoline using their 89 octane. Doing that, you can save even more per tankful. Why anyone would want to save around two to three dollars every time they fill the tank by using a lower grade of inferior gasoline on a car like a BMW is beyond me. :(

If you want to use the gas that BMW recommends for optimal performance, then spend a little more money on 91 octane Top Tier gas and get the best. To me, that's a no-brainer.
Winner winner chicken dinner.
 
#38 ·
No. Minimum. If you can't get 91 octane. BMW says the motor is designed for 91 octane. That's the grade EPA indicates is used to achieve the stated fuel mileage ratings. You bought a BMW. The difference in gas expense over a year is barely over $100.

New model. New buyers. I guess we're going to have this discussion again for the next three years. :rolleyes:
 
#41 ·
+1

:bigpimp:

Use 91 Octane. End of Discussion !:thumbup: This topic is getting So TIRED !!!

:bigpimp:
 
#40 ·
useful discussion of the subject here;

http://www.rs6.com/showthread.php/10280-Power-loss-at-altitude-with-a-Turbocharged-engine

Theoretically turbocharged cars lose ZERO power at altitude, but to do this the ECU has to be able to change the boost level to allow more airflow into the engine... which usually it is not able to completely do, so usually turbocharged cars DO lose a bit of power at altitude but it is a fraction of what a NA car loses.

To put it another way, at 6500 feet a 328i with an I6 is losing about 25% or so power. The N20 is probably losing something like 5-10% power. Big advantage, which is why turbocharged cars are quite popular in Colorado (and, I imagine other high altitude areas).
 
#42 ·
useful discussion of the subject here;
...To put it another way, at 6500 feet a 328i with an I6 is losing about 25% or so power. The N20 is probably losing something like 5-10% power. Big advantage, which is why turbocharged cars are quite popular in Colorado (and, I imagine other high altitude areas).
That raises an interesting side question to this discussion.

I live in CO at 8400'. Our octane is 2 points lower than sea level locations. I've never factually determined the altitude at which this change in gasoline formulation is made, but observation of gas stations while traveling I'd guess it's around 3000' to 4000'. So, living at 8400' (and commuting to 6200') most of my driving is well above the altitude corresponding to a 2 point octane reduction so using mid-grade is equivalent to using premium a few thousand feet lower.

But...is this still true with the N20 turbocharging? My only experienced with turbocharging is on my VW Jetta TDI, but being a diesel it's an entirely different story. Does the N20's turbo management maintain boost sufficiently to noticebly reduce the octane requirement reduction with altitude?
 
#44 ·
Manual says 89 will cause knocking, to me that is not good even though manual says it has no effect on engine life...hard for me to believe and I'm no engineer.
89 should work if you are in higher elevation like Denver but when you go sea level switch to 91.
I would stick with 91.
Don't waste your money on 92 and higher.
 
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