[nZtiZia]

Originally Posted by dombi

Diesel BMW owner here. I talked to the service guys at the dealership, about this several times. I asked them whether I should fill up with premium.

filling up a diesel with premium unleaded fuel

still, if you’re talking about diesel fuel, that’s not what this thread is about

additionally, you misunderstood jad03060 post and the difference between BMW minimum and recommended fuel rating. I suggest reading it again, but I’ll go ahead and explain it:

using the minimum 87, the engine may knock (per the manual), so BMW did optimize the engine for premium (91+), not 87

[TurtleBoy]

Originally Posted by nZtiZia

filling up a diesel with premium unleaded fuel

I assumed he is talking about Premium diesel.

[nZtiZia]

Originally Posted by TurtleBoy

I assumed he is talking about Premium diesel.

there’s such a thing? every gas station (US) I’ve been to in over 30 years has one diesel pump

EDIT: apparently there is. I’ve just never seen it

[raw2210]

Originally Posted by TurtleBoy

The picture exceeds the max pixels so it is automatically rotated. Here it is resized to be 900 x 1200, I usually use 1200 as the max side.

Thank you TB for the explanation!

I have been accused of being a 1/2 bubble off plumb. Mostly by my wife. Thought that was why I couldn't get it straight.

After 4 tylenol, my headache is finally going away.

[eelnoraa]

UK octane rating unit is RON. 95 RON = 91 AKI in US.

Don’t get caught with the name of the fuel grade.

[BMPHIL]

Originally Posted by eelnoraa

UK octane rating unit is RON. 95 RON = 91 AKI in US.

Don’t get caught with the name of the fuel grade.

You can't buy lower than 95 RON in UK at petrol station.

[Kgerry59]

I always gas up at Shell (for the Air Miles) and always use Premium.

[ekaz]

Man, these gas threads always ruffle feathers no matter the car/brand. Just to add, always use premium, the cost difference really isn't much when you look at it.

[eelnoraa]

Originally Posted by ekaz

Man, these gas threads always ruffle feathers no matter the car/brand. Just to add, always use premium, the cost difference really isn't much when you look at it.

Between 87 and 91, it is $0.4 difference. It represent 10% different in my area $4.27/$4.67. If gas is cheaper else where, the percentage can be large. let's say 40i will average 22mpg. annual mileage 12k. We are talking about $220 difference per year. Yeah, hardly makes a dent

[Gibson6594]

Originally Posted by eelnoraa

Between 87 and 91, it is $0.4 difference. It represent 10% different in my area $4.27/$4.67. If gas is cheaper else where, the percentage can be large. let's say 40i will average 22mpg. annual mileage 12k. We are talking about $220 difference per year. Yeah, hardly makes a dent

I have experienced better milage using premium, so I think that number is potentially lower.

[jad03060]

Using the recommended octane will let the engine run more efficiently, with potentially more power at lower RPM, allowing it to get into top gear sooner, and save fuel overall. So, whether it ends up cheaper than using the minimum depends on the cost difference of the two varieties where you live.

Note, if you can find fuel without ethanol, your MPG will improve, too, as pure gasoline/petrol has more energy per volume than the ethanol that replaces it. In many markets, you have no choice, but in some, you do.

[eelnoraa]

Originally Posted by Gibson6594

I have experienced better milage using premium, so I think that number is potentially lower.

Yes, I was trying to give the most margin. even that , not much

[raw2210]

Originally Posted by eelnoraa

Between 87 and 91, it is $0.4 difference. It represent 10% different in my area $4.27/$4.67. If gas is cheaper else where, the percentage can be large. let's say 40i will average 22mpg. annual mileage 12k. We are talking about $220 difference per year. Yeah, hardly makes a dent

It's $1.00 a gallon difference here.

[iX nOOky]

Originally Posted by jad03060

Using the recommended octane will let the engine run more efficiently, with potentially more power at lower RPM, allowing it to get into top gear sooner, and save fuel overall. So, whether it ends up cheaper than using the minimum depends on the cost difference of the two varieties where you live.

Note, if you can find fuel without ethanol, your MPG will improve, too, as pure gasoline/petrol has more energy per volume than the ethanol that replaces it. In many markets, you have no choice, but in some, you do.

The best we have here is 91 octane with no ethanol but it's about $1 a gallon more than 87 octane. I'll use it because $20 a week won't break me, that's just over one pack of cigarettes and I don't smoke so I'll call it money well spent.

[low2ground]

The fuel efficiency of the mild hybrid essentially cancels out the extra cost for high test. Either way, a couple hundred bucks for gas was never going to sway my decision about ordering an X5. If I wanted to save a few bucks on octane, I'd buy a middling SUV. The X5 is not a middling SUV.

[walketed]

Originally Posted by sarpal123

It’s finally become time, after six months, to put some fuel in my 50e and before I do, here’s what’s been going through my mind (be kind, please).

Here in the UK we’ve been conned by reducing the grade of the standard fuel and then calling the previous regular fuel “Premium” (and charging more for it) – but that’s another story.

Although the 50e will run on both E10 (95 Octane) and E5 (Premium unleaded) I’m considering filling up with E5 as it will sit in the tank for months as I understand that E10 can hold water in suspension.

For the nominal cost increase of a tank of fuel over 6-9 months does E5 make sense or am I just overthinking it and just save a few quid with E10. I assuming that 97/98 RON (Super unleaded) is a step too far.

Really? This is not a Corolla, just use the highest octane/quality gas for your car.

[dombi]

Originally Posted by nZtiZia

filling up a diesel with premium unleaded fuel

still, if you’re talking about diesel fuel, that’s not what this thread is about

additionally, you misunderstood jad03060 post and the difference between BMW minimum and recommended fuel rating. I suggest reading it again, but I’ll go ahead and explain it:

using the minimum 87, the engine may knock (per the manual), so BMW did optimize the engine for premium (91+), not 87

Thanks. Here, in Europe we actually have premium diesel. Which is also not the recommended fuel to use.

I was just putting my own 2cents in.

[sarpal123]

Just to get back on track...

This was never about the cost of fuel. It was understanding the most effective/efficient use of fuel - and bang-for-buck (pun intended) is just one part of the equation. Also, my other thought was the potential "risk" of storing ethanol containing fuel for an extended period - is 9 months an extended period?

In amongst the comments so far, there are answers to these questions so, thanks for the knowledgeable responses!

[nZtiZia]

Originally Posted by sarpal123

Just to get back on track...

This was never about the cost of fuel. It was understanding the most effective/efficient use of fuel - and bang-for-buck (pun intended) is just one part of the equation. Also, my other thought was the potential "risk" of storing ethanol containing fuel for an extended period - is 9 months an extended period?

In amongst the comments so far, there are answers to these questions so, thanks for the knowledgeable responses!

fuel sat in my 45e tank for 7 months straight...twice...between 2020-2021 when we weren't taking any road trips. no issues with vehicle performance either time (even now), so safe to say no issues with the sitting fuel (US Exxon, 91 octane E10 fuel)

if you say E5 costs just nominally more than E10, just get E5, but with the 50e's pressurized and sealed tank, E10 fuel doesn't appear to be an issue for extended periods

[davchr]

Originally Posted by BMPHIL

95 octane
The standard rating for petrol in the UK is 95 octane, and every car sold in the UK has its electronics tuned so that it can run properly on this fuel. In some foreign countries, you can get lower octane rated fuels, but if you add these to your car, it may cause 'knocking'.

There are different octane ratings - Research (RON), which is used in Europe, Motor (MON), and (RON + MON) / 2, which is the average of RON and MON, which is used in the US. When comparing octane numbers worldwide it is nice to specify which one is being discussed.