[mattcgy]

Hey all,

I live in calgary, canada, which has an elevation of around 3700 feet, I drive 99% of the time at this elevation or higher (when going to the mountains) have always put in 91 octane, but heard about how octane because higher at higher altitude due to compression, what would your thoughts be on putting 87 in or 89 at 3700 feet? Companies gouge for premium fuel here, its normally like 17 cents more per litre, only costco has it at 10 cents more per litre, unlike in the usa where premium isn't such a huge difference!

 

[melk81]

Premium is usually +0.30 cents here per gallon, fwiw.

As far as running 87 octane goes.... try it? Only way to know for sure.

 

[mattcgy]

Yea i was just wondering though, due to elevation would 87 not ping because of compression.

Yeah, its usually a difference of 15 per litre here so like a 56 cent per gallon difference.

 

[bachusattackus]

Not pinging will be because of knock sensor that will retard the timing of your engine. Then you will not have as good of fuel economy.

If Mercedes intended for the car to be run on less then 91 octane due to high elevation it would say so in the owner's manual. It doesn't.

Running an M111 engine on 87 octane will result in chronic predetonation, potentially leading to increased valve wear. If you are filling up, you will save about $5.70.

Subtract reduced fuel economy and the savings are a bit less. Add in the increased cost of carbon deposits, destroyed knock sensor, a potential valve job and you will eventually wished you had listened to the people who designed and built your engine.

On days when you need to fill up, see if you can find another way to save $5.70.

 

[W202 Kompressor]

You drive a mercedes, which isnt a cheap car to begin with. Using a lower grade gas will destroy a $5,000 (estimated) motor. By going with a lower grade You are saving $0.01 per mile. Which probably amounts to less than $50 a year. If you ask me, its just not worth it. If saving $$ is your concern, then maybe you ought to consider another brand of vehicle which does not have such high maintenance costs.

In other words, your investment of 0.30 cents per gallon will never pay dividends in the long run.