Put 93 in. If you put 87 in you will lose MPG and it will equal out to the same amount as if you had bought premium. If you want to try....go for it...just keep a log book and you will see.

 

I submit that:
A) If you don't push your car to achieve maximum performance (I think this would describe most drivers), then you won't be affected by the loss of power. The loss of mpg also "depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique" so it seems the mpg loss can be overcome by the conscious driver. This idea seems to be supported at least anecdotally.

and BMW "motors will run on 89 or 87 octane without damage". There is no risk to your vehicle from lower octane fuel. He does go on to mention "the type and quality of additives the gasoline companies include in the fuel", and goes on to say, "Premium gasolines may have better additive packages", and that "Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line." But this has nothing to do with the octane of the gas, rather which additives are put in. (Which is why I would choose a top-tier gas station like Shell, who adds "V-power" additives to their product).

If you don't care about peak performance, then you are justified in saving a few bucks at the tank. If a few bucks is a big deal to you, then no, you obviously cannot afford a premium car. However, the principle of being thrifty is a sound one. Even if you only save enough for a cup of coffee, you can enjoy that cup of coffee rather than giving it to the oil companies for no good reason.

 

excerpt from the article on roadfly -
"Bottom Line: Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the immediate savings at the pump may be wiped out by the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time."

'nuff said.

 

i always use 97, car runs like a swiss watch, £1.46 UK pounds per litre x 3.78 litres = £5.58 = USD$8.94/gal

the lowest available locally is 93

 

It's measured differently in Europe than it is in the US. Your 97 is the same as 91 in the US - the measurement scale used here isn't quite the same as it is over where you are.

 

It is common ground between pretty much everyone who has posted in the thread - and has been since post two - that the car can run fine on lower octane fuel than BMW recommends. It is also common ground that the car will lose something in the way of performance potential and in fuel economy. Simply put, your actual gain from using regular will, in all likelihood, be close to zero - and it may even be costing you more than it would had you filled up with premium. It won't take much of a reduction in actual MPG, a reduction that it is generally accepted will happen if you use lower octane fuel, to wipe out any savings. It is perfectly possible that you could perhaps even be spending more that you would otherwise have spent following BMW's recommendations due to a reduction in MPG.

I'll be blunt - if someone is filling up their car with regular for the reasons you state it is little short of idiotic. Having your car run to the best of its abilities is worth much, much more to most of us here than what is, literally, a savings of a few bucks per tank. Anyone in a 5 Series or similar who is described by some of your statements - and I have bolded them above - probably did buy the wrong car...

 

Let's not beat a dead horse. On second thought, let's.

Am I the only one that sees a contradiction in the quoted statement? In essence it says that running lower octane will not hurt the cars, however in the same breath it also says you are opening up yourself for damage "over time".

Which is it?

For my money, I will run what the engine is designed for. Now when my local stealer starts recommending and selling BMW-branded premium gasoline, I will then question whether premium is really necessary.

 

you learn something every day, thanks it makes sense

as an aside, when i was racing bikes 10 years ago, leaded petrol was phased out here. the same year we ran two superstock engines, one on regular 93 ( i assume 87 US or similar ) and one on premium ( only 0.5bhp difference on a dyno ) at the end of a season's racing we stripped both motors, inside the head that ran on regular fuel everything was black. inside the one on premium was clean so there is some truth in the marketing blurb.

 

You must examine the entire article to understand the "bottom line", and you will realize there is in fact no contradiction in the statements at all. The "possibility of damage over time" refers to paragraph 5 which states:

"Premium gasolines may have better additive packages which are more effective keeping fuel systems (particularly injectors) clean and working efficiently, than those in regular grade fuels or off-brand products. Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line."

This paragraph states that some fuel brands include better additives in their premium product, making the lower grades inferior. If you use a top tier gas that puts these additives in all grades, you can avoid this problem, (which is why Mr. Plucinsky calls it a "possibility" not a certainty), and again, this issue is separate from the question of whether 87 is bad for your car. It clearly is not.


The article also states in paragraph 6:

"It would seem a determined deranged drag racer could run Regular in his Corvette and, over time, he might manage to melt a piston or two."

This also supports the statement that over time you could do damage to the engine, however this statement applies only to supercharged vehicles which run higher compression. The OP has a 530i, so this statement does not apply.

So yes, you can damage your car using regular if 1) you use cheap quality gas with inferior additive packages (a more important factor than octane), or 2) you have a high compression engine (which the OP does not)

 

I agree that it is common ground that something "may" be lost from using 87, however whether or not that something is enough to offset the difference in price is still up for debate. There is by no means a clear cut answer to this question, because so much depends on outside factors, which is why BMW hesitates to make the claims you do.

"the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels."

I will say this, if you indeed lose MPG using regular gas, then this will obviously outweigh the benefits of switching from premium. However, it does not appear to be a certainty that this will happen, and browsing the web will yield differing opinions. I think this is due to the many factors involved with the MPG number, precisely the point that Mr. Plucinsky was making.