[DrRT]

General question for you guys.

Would you say (for any engine, not just BMW) that higher octane gasoline gives better mileage? Perhaps so much so that it is CHEAPER overall to pay more for higher quality gasoline (because you get better mileage).

Thanks.

[panzer948]

The general theory on this is No. Not worth it. Just put the minimum required.

[F32Fleet]

Originally Posted by DrRT

General question for you guys.

Would you say (for any engine, not just BMW) that higher octane gasoline gives better mileage? Perhaps so much so that it is CHEAPER overall to pay more for higher quality gasoline (because you get better mileage).

Thanks.

No. As a general rule of thumb high Octane fuels are needed for high compression engines. Using lower ocatane fuels in these types of engines will cause the engine to retard timing, loose power, get worse mileage (a couple of mpg).

Low compression engines (most american cars for example) would not benefit unless they are older engines.

[Chesmu]

that being said, using the 87 vs. 91 will save you maybe 100.00 per year. I think using the higher octane helps the car run better, and it's worth the hundred bucks for my (maybe erroneous) piece of mind.

[Joop!]

Originally Posted by Socom

No. As a general rule of thumb high Octane fuels are needed for high compression engines. Using lower ocatane fuels in these types of engines will cause the engine to retard timing, loose power, get worse mileage (a couple of mpg).

Low compression engines (most american cars for example) would not benefit unless they are older engines.

You're absolutely right

[StewtheBassman]

Petro Can 94 is like reflashing my car.

[rrandyy]

Originally Posted by Chesmu

that being said, using the 87 vs. 91 will save you maybe 100.00 per year. I think using the higher octane helps the car run better, and it's worth the hundred bucks for my (maybe erroneous) piece of mind.

My understanding is that the higher octane fuels prevent knocking on high performance engines because they are more resistant to igniting before the sparkplug detonates (is that the right word?). Also, I have been repeatedly been told (for example, on my jetskis) that using a higher octane than required gas not only does not benefit me, it actually hurts the engine because it leaves behind more residue (maybe this is only a symptom seen when mixing with 2-stroke oil?).

Bottom line, its $100/per year that you are throwing away. Instead, send it to me. PM me for paypal info.

[canucklion]

for some odd reason, we dont have 94 in Ontario's Petro Can stations

Originally Posted by StewtheBassman

Petro Can 94 is like reflashing my car.

[Chesmu]

we don't have CANADIAN gas in AMERICA...


i really don't have any idea what my point is....

[neuronpetkowski]

Originally Posted by Chesmu

we don't have CANADIAN gas in AMERICA...


i really don't have any idea what my point is....

"Canadian gas." That anything like canadian bacon? It's pork, but it's "canadian?"...i kid.

I remember in Michigan, getting 94 octane from Sunoco. Stuff was great. But I probably didn't need it for a Ford F-150...

[epiphone3]

Originally Posted by DrRT

General question for you guys.

Would you say (for any engine, not just BMW) that higher octane gasoline gives better mileage? Perhaps so much so that it is CHEAPER overall to pay more for higher quality gasoline (because you get better mileage).

Thanks.

Long story short:

A BMW engine will be CHEAPER over all if you run it on higher octane fuel (unless boosted with ethanol). If you read the standard features, you will see "Cylinder specific knock control" in the engine category... what that means is that the computer will detect the Octane level of the fuel you are using and will advance or retard the ignition timing based on this. Higher Octane will allow the computer to advance timing more without getting knock and hence allow you to get the more optimum burn you are looking for. This will improve your fuel economy (not to mention the engine's perormance) to the point where you will at least recover the extra cost of the premium fuel (usually like 7 cents per liter) or come in a little cheaper. So, you at least break even on the fuel cost and on top of it, you get the cleaning solvents/additives included in Premium fuel which will save you money in the long run in the form of reduced maintenance costs. IT IS CHEAPER.

Other engines... you will only benefit from improved gas mileage and performance with higher octane gas if the car has knock control or if you go to the trouble of adjusting the ignition timing to take advantage of the premium fuel.

These are the facts.

[epiphone3]

Originally Posted by StewtheBassman

Petro Can 94 is like reflashing my car.

FOR SURE! I wish we had that here in Calgary... I drove my car across the country this summer and got a tank of Petro Canada 94 in Gaspe. Man did my E90 like that stuff... liked it even more than Shell V-Power!

[StewtheBassman]

Funny you should say that. I ran a couple of tanks of 91 V-power and it felt like the engine was the old E46er...Emptied it out and then refilled it with 94 and POW!!!!

Neuron your revised sig pic is funny!

[Jaws]

Originally Posted by epiphone3

Long story short:

A BMW engine will be CHEAPER over all if you run it on higher octane fuel (unless boosted with ethanol). If you read the standard features, you will see "Cylinder specific knock control" in the engine category... what that means is that the computer will detect the Octane level of the fuel you are using and will advance or retard the ignition timing based on this. Higher Octane will allow the computer to advance timing more without getting knock and hence allow you to get the more optimum burn you are looking for. This will improve your fuel economy (not to mention the engine's perormance) to the point where you will at least recover the extra cost of the premium fuel (usually like 7 cents per liter) or come in a little cheaper. So, you at least break even on the fuel cost and on top of it, you get the cleaning solvents/additives included in Premium fuel which will save you money in the long run in the form of reduced maintenance costs. IT IS CHEAPER.

Other engines... you will only benefit from improved gas mileage and performance with higher octane gas if the car has knock control or if you go to the trouble of adjusting the ignition timing to take advantage of the premium fuel.

These are the facts.

I don't buy your "facts". In my experience, there has been no noticable difference in fuel economy when I have filled my cars with premium vs regular (the recommended gas in both cases was premium). I have experimented with a Maxima and Volvo 850 and have concluded there is no difference. Just because a car can generate more power with the timing advanced doesn't mean that it will get better economy. Additionally, I can see where serious knocking will damage an engine, but I have yet to see any proof that ocassional light pinging will do any damage (most manufacutures claim it won't). Knock sensors will prevent any serious damage. I cannot see reduced maintenance cost as being a reason to use premium fuel. I use premium in the summer b/c I do notice a seat of the pants difference vs regular. In the winter I use regular. The S2000 always gets premium (11:0 to 1).

[canucklion]

man, I'm missing out on the good stuff then!:mad:

Originally Posted by StewtheBassman

Funny you should say that. I ran a couple of tanks of 91 V-power and it felt like the engine was the old E46er...Emptied it out and then refilled it with 94 and POW!!!!

Neuron your revised sig pic is funny!

[Jaws]

Originally Posted by canucklion

man, I'm missing out on the good stuff then!:mad:

Me too:mad:

[Jaws]

Originally Posted by Chesmu

we don't have CANADIAN gas in AMERICA...


i really don't have any idea what my point is....

But you get a lot of Canadian oil. No point here either.

[canucklion]

me think Chesmu secretly wants to be Canadianized

[StewtheBassman]

They want our water too lol!!

Guys about all we have good in Quebec is 94 Octane and beautiful women!!

[ScheerSpeed]

well, from my experience in race cars, a higher octane gasoline will run the engine at a cooler temperature, resulting in more horsepower (the change is minimal) i always like the best for my car, so i normally would use the highest octane i can find. Higher octane gasolies also burn much cleaner (less pollution), lasts longer, and promotes your engine to be cleaner. Lower octane gasolies have a tendency to build up grime on your intake valves, which can restrict air flow into the motor (resulting in less HP). But if you want to use the 91 im sure it will not be a problem, here in Miami i always use 93. sometimes 100 if i can get my hands on it at the race car shop. you also dont want to go too high. It mostly depends what you want your car for: everyday driving, or performance. everyday you can use 91 no problem, but for performance go with the 94 94=

[epiphone3]

Originally Posted by Jaws

I don't buy your "facts". In my experience, there has been no noticable difference in fuel economy when I have filled my cars with premium vs regular (the recommended gas in both cases was premium). I have experimented with a Maxima and Volvo 850 and have concluded there is no difference. Just because a car can generate more power with the timing advanced doesn't mean that it will get better economy. Additionally, I can see where serious knocking will damage an engine, but I have yet to see any proof that ocassional light pinging will do any damage (most manufacutures claim it won't). Knock sensors will prevent any serious damage. I cannot see reduced maintenance cost as being a reason to use premium fuel. I use premium in the summer b/c I do notice a seat of the pants difference vs regular. In the winter I use regular. The S2000 always gets premium (11:0 to 1).

Okay... if you want to just disagree with science its your problem. All I know is what I have observed through some personal experimenting and experimenting with friends vehicles.... oh yeah, and I what I learned with my Energy system - focused Mechanical Engineering Degree.

Maybe the maxima and the volvo don't have what is required to fully take advantage of premium or maybe you just pushed them harder when you used it.

[whippersnapper]

The funny thing is higher octane fuel has a lower energy density, so the lowest octane fuel that allows for optimum ignition timing will produce the most power.

So old nail engines work best on 87 and very high compression engines (e.g motorcycles) work best on 93. Best to use whatever fuel octane rating the manufacturer recommends. They don't specify premium lightly because they know that a segment of customers is turned off by the need to pay more at the pump.