[ColoM40i]

Does BMW state in writing that using 91-93 octane gas is required to prevent damage and voiding warranty? Or.....do they say 91-93 octane is recommended for best performance and gas mileage.

My Kia Stinger GT 365 HP/6000rpm, 376 LB/FT torque 1300-4500 RPM,
Twin Turbo, 0-60 4.6 seconds does not require 91-93 octane. The Kia Stinger manual simply states "using unleaded gasoline with an octane rating lower than 91 could result in loss of engine power and increase in fuel consumption".

I here so much talk about burning premium gas in a BMW is a must.
I like the flexibility of being able to run both regular and premium.

[ga9213]

89 is the required min. 91 recommended.

[Pray for Mojo]

This stuff is kind of mind blowing to me. You have an expensive luxury SUV but are willing to gamble a bit on it's longevity to save <$10 a tank.

[ga9213]

Owner's manual:

Recommended fuel grade
BMW recommends AKI 91.
Minimum fuel grade
BMW recommends AKI 89.
If you use gasoline with this minimum AKI Rating,
the engine may produce knocking sounds when
starting at high external temperatures. This has
no effect on the engine life.

[ColoM40i]

Originally Posted by Pray for Mojo

This stuff is kind of mind blowing to me. You have an expensive luxury SUV but are willing to gamble a bit on it's longevity to save <$10 a tank.

Have you written proof (not just another opinion) that 91 octane extends engine longevity or are you just speaking urban legend?

[ga9213]

Originally Posted by ColoM40i

Have you written proof (not just another opinion) that 91 octane extends engine longevity or are you just speaking urban legend?

If the vehicle is tuned for it (and it is) power will be reduced as timing is pulled due to the detection of detonation with lower grades of fuel than tuned for.

Detonation itself is damaging but usually curbed with the power reduction.

So yes, the recommended octane can improve longevity by avoiding detonation but more likely all you'll ever experience is just power reduction.

As long as you don't go below the min threshold. 89 isn't that much cheaper than 91...so you're not talking 10 dollars a tank, but more like maybe a couple bucks.

[ColoM40i]

Originally Posted by ga9213

89 is the required min. 91 recommended.

Same thing my Stinger manual says. I like the higher performance with 91 when I want to and still strong but not max performance with 89. Not once have I heard a ping or knock burning 89 octane.

[ga9213]

Originally Posted by ColoM40i

Same thing my Stinger manual says. I like the higher performance with 91 when I want to and still strong but not max performance with 89. Not once have I heard a ping or knock burning 89 octane.

You don't have to hear it for it to be occurring.

The fuel itself isn't what's making a difference in power. That power loss is because the ECU pulled the power because it detected knock.

You were likely safely running 89 but every time the ECU attempted to give back some timing it would see knock again and keep your power curbed.

Just as you'd likely safely be able to run 89 in the BMW too...but is the power reduction worth saving a buck or two at the pump once a week or however often you fill up?

Seems silly to me...but your choice.

[ColoM40i]

Originally Posted by ga9213

If the vehicle is tuned for it (and it is) power will be reduced as timing is pulled due to the detection of detonation with lower grades of fuel than tuned for.

Detonation itself is damaging but usually curbed with the power reduction.

So yes, the recommended octane can improve longevity by avoiding detonation but more likely all you'll ever experience is just power reduction.

As long as you don't go below the min threshold. 89 isn't that much cheaper than 91...so you're not talking 10 dollars a tank, but more like maybe a couple bucks.

There is no detonation. You know that all modern engines have a knock sensors and will adjust the timing accordingly. The small power loss I agree.
It is not a matter of being cheap. It is a matter of waste.

[Pray for Mojo]

Originally Posted by ColoM40i

Have you written proof (not just another opinion) that 91 octane extends engine longevity or are you just speaking urban legend?

One of my favorite things is watching online misers talk about how they trip over dollars to save pennies on massively depreciating assets. Like the $8.50 a tank will help with the hundreds of dollars a month that vanishes into thin air while it sits in your garage or rolls down the road.

The fact premium fuel exists dispels any myths or urban legends about its purpose. Higher octane fuel prevents detonation and knocking, where a large force hammers down on your rods and bearings at the the worst possible moment causing mechanical wear and damage.

Can you get by driving like a grandma with 87 in the tank, probably, does it defeat the purpose of purchasing a sports car/SUV, undoubtedly yes. You have to pay to play, if you won't even put the recommended fuel in are you going to cut corners on maintenance expenses as well?

[ColoM40i]

Originally Posted by ga9213

You don't have to hear it for it to be occurring.

The fuel itself isn't what's making a difference in power. That power loss is because the ECU pulled the power because it detected knock.

You were likely safely running 89 but every time the ECU attempted to give back some timing it would see knock again and keep your power curbed.

Just as you'd likely safely be able to run 89 in the BMW too...but is the power reduction worth saving a buck or two at the pump once a week or however often you fill up?

Seems silly to me...but your choice.

Would you please refer me to something (not an opinion) in writing from a reputable source that supports what you say. I'm hearing and reading too much that running regular in todays modern engines does no harm short or long term. I think BMW is telling you the same thing.

[ColoM40i]

Originally Posted by Pray for Mojo

One of my favorite things is watching online misers talk about how they trip over dollars to save pennies on massively depreciating assets. Like the $8.50 a tank will help with the hundreds of dollars a month that vanishes into thin air while it sits in your garage or rolls down the road.

The fact premium fuel exists dispels any myths or urban legends about its purpose. Higher octane fuel prevents detonation and knocking, where a large force hammers down on your rods and bearings at the the worst possible moment causing mechanical wear and damage.

Can you get by driving like a grandma with 87 in the tank, probably, does it defeat the purpose of purchasing a sports car/SUV, undoubtedly yes. You have to pay to play, if you won't even put the recommended fuel in are you going to cut corners on maintenance expenses as well?

Cool down Mr. high roller. It is not a matter of money. It is a matter of waste. Post some proof.

[sbt007]

I read up on this when I mistakenly filled up my 3 series with regular and just used up that tank and switched back to premium. AFAIK the engine remaps itself to the new octane and reduces performance but is otherwise fine in the short term. As to whether it may cause long term harm, I have no idea.

However I don't think you are reducing waste. This is because you might now get lower MPG and fill up a little sooner.

[Pray for Mojo]

Originally Posted by ColoM40i

Cool down Mr. high roller. It is not a matter of money. It is a matter of waste. Post some proof.

Run the experiment for the board, two tanks of regular, two tanks of premium. Calculate the difference in MPG and price and see if you are actually saving more than a couple $.

[ColoM40i]

Originally Posted by Pray for Mojo

Run the experiment for the board, two tanks of regular, two tanks of premium. Calculate the difference in MPG and price and see if you are actually saving more than a couple $.

Get on the internet and do some research. Source after source after source say the same thing.....If the manufacturer states premium REQUIRED than you should. If they state premium RECOMMENDED, it is not necessary or required to protect your engine. They are only stating that you could (not would) get better performance or better gas mileage. It would be nearly impossible to do your experiment and obtain accurate results. One would have to drive the exact same routes, accelerate the same, carry the same vehicle load, operate in the same driving modes, drive with & against the wind the same, hit the same traffic lights etc., etc. Again, go to the internet. There are examples showing that premium vs regular yields very little additional performance or increased gas mileage. Go do some research

[mreg376]

Originally Posted by ColoM40i

There is no detonation. You know that all modern engines have a knock sensors and will adjust the timing accordingly. The small power loss I agree.
It is not a matter of being cheap. It is a matter of waste.

If you consider getting top performance from your luxury (and luxury-priced) vehicle "a waste" you should have gotten a Honda that runs on regular gas. The "waste" is your having a BMW.

[ColoM40i]

Originally Posted by sbt007

I read up on this when I mistakenly filled up my 3 series with regular and just used up that tank and switched back to premium. AFAIK the engine remaps itself to the new octane and reduces performance but is otherwise fine in the short term. As to whether it may cause long term harm, I have no idea.

However I don't think you are reducing waste. This is because you might now get lower MPG and fill up a little sooner.

I was referring to a waste of money. Be very honest. Did you immediately notice a lack of performance after pumping regular or did you just think there was going to be a lack of performance because you heard there would be.
Can you honestly say you saw reduced gas mileage?

[ColoM40i]

Originally Posted by mreg376

If you consider getting top performance from your luxury (and luxury-priced) vehicle "a waste" you should have gotten a Honda that runs on regular gas. The "waste" is your having a BMW.

Come on now.... I can detect you're getting cranky. Be nice

[Little tomato]

Originally Posted by ColoM40i

Come on now.... I can detect you're getting cranky. Be nice

I think that was nice.

[mreg376]

Originally Posted by Little tomato

I think that was nice.

But he's right. I'm generally cranky. :-)

[ga9213]

Originally Posted by ColoM40i

There is no detonation. You know that all modern engines have a knock sensors and will adjust the timing accordingly. The small power loss I agree.
It is not a matter of being cheap. It is a matter of waste.

You're talking to someone who tuned 5 of my prior vehicles, so please don't ask such silly questions about what I know.

A knock sensor detects....knock. It adjusts timing because it saw...knock.

So yes, there is detonation. The knock sensor sees enough detonation to reduce timing advance tables in the rpm/load columns it continually sees knock in. Over time it will try to reduce the timing modifiers to see if you're running better gas. As it sees knock, it will reduce the timing again.

So if you're going to ask a question from folks please consider listening instead of talking.

[chassis]

Follow the manufacturer's recommendation.