I see people keep saying things like there aren't facts, etc - or talking about valves and coking, or catalytic converters.

No - this guy is right, and they are facts. This is based on how the engine controls fueling.

The valve coking/cat damage issues are related to O2 sensors and AFR - running too rich will cause excess buildup on valves and damage the catalytic converter in short order. Running too lean will cause damage similar to running too low of octane. However, these things are not related. Octane does not impact AFR or the stoichiometric values for the fuel. That is all based on O2 sensors, air sensors, and fueling maps with feedback loops, regardless of octane.

Octane matters because there are considerations of timing and adjustments to fueling based on temperatures by expected octane. This is why the required octane is factual, not opinion. There is a baseline set of parameters in the ECU that it starts from, which controls timing, fueling, etc. Knock sensors, O2 sensors, etc are all used to adjust this set of parameters based on the variances in fuel, altitude, engine assembly, etc. However, it is only designed to make these adjustments within the tolerances of the fuel of the grade listed.

So if 91 is listed, the baseline parameters expect variances within the boundaries of what can be labeled '91'. It is entirely likely that these parameters will not handle fuel labeled '89' - but not 100% guaranteed, which is why people have success. As the quoted poster mentioned, the engine must first encounter an issue to make these adjustments, and as also mentioned, it only takes one bad preignition/predetonation event to destroy an engine. If you get lucky, you'll first have several events that are non-damaging, the sensors will notice it, and it will make corrective adjustments to all the maps, which will cost you power and usually also fuel efficiency in order to protect itself.

So either scenario is losing, it's just a question of how bad.

Edit: Worth mentioning, the parameters do generally also provide some room the other direction, so if you have 93, generally it will learn some advance and you'll make a bit more power. Temperature is a cruel mistress for this one though, as summer heat can make it dangerous even with decent octane fuel.

However, do not buy into the people who say "Look I've done it, my car didn't explode, so it's totally fine!" It's right up there with playing Russian roulette because another guy did and lived.

 

I never got why someone who pays $30,000 for a car tries to save $3 on a tank of gas knowing there's potential to screw up his car. Then he buys a pack of smokes in the store for $8!

 

LMFAO...

ah men brother. Well said.

 

Suggestion: Hire lawyer to draft a letter asking your employer VP of HR to sign. Stating that he or she is personally responsible (and the company too) for any damage as the result of using fuel not to specification. That if there is any retribution against you, they both will have a law suit on their hands. If they hired you when you had the Mini, even better. Did you sign any firm that staged you 1.) could pay difference between their approved fuel and something better 2.) you signed something next to specific language about the fuel?

Also, go to Mini dealer or call Mini and ask them to send a personal letter to the nameless faceless greasy pony tail cubicle rat VP of HR that Mini will not honor the warranty because of sustained forced use of substandard fuel.

If you live in CA or a labor friendly state, context organizations who deal with HR issues. Also complain to the State AG.

Unless you live in a at will state (fire without cause), you have some protection. Of course, if you are a minority, or feel like you are in process to change gender while in this this battle, that these may help create extra concern from your employer.

Points are, you have a legit grievance. They do not even have a way for you to pay the difference (do not give this away quick, can always be used in a settlement later). What if you decide to go out and buy a used gas guzzling something that uses regular? They would pay more than arguing with you.

All above in good dreaming of possibilities. Not unpaid advice.

 

One more thing. If you are over 40 or 45, most states you have protection from age discrimination. Federally too. Not trying to be a socialist, dreaming of methods of indirect leverage.

 

Yeah ruin your career and employment for some octane, great ideas.

 

I had an old 2000 Saab 9-5 V6 with a low pressure turbo that requires (or recommends) premium gas. It had about 90k miles when I bought it for $3000, initially meant to use only for couple months during an internship. I liked the car a lot and was reliable so I drove that from MA to OR and then sold it after couple more months of fun.
I used premium at first but then switched to regular. On 100% highway I got about 10% better gas mileage with premium, but in city or mixed driving it was hard to tell any differences. I'm guessing it can make more power due to better timing with premium gas (or you can say it makes less power with normal gas due to timing changes). I never experienced knocking, which means the sensors are doing a good job, and also there are cars that can run regular but take advantages using premium gas, Hyundai Genesis being one of them. From that, I think the knock sensor should be able to be used regularly to control the timing without any real damage. The sensor should retard timing as soon as it senses a tiny knock which is not dangerous, and I don't think the sensor wears out from relying on it. But that's just my thought, I have no background in internal combustion engines so don't quote me on this if your engine blows up from using regular gas.

I do fill my F56 with premium all the time.

 

I would only add...

Not using proper octane rating suggested by manufacturer will cause Detonation, and while that in and of itself not "damaging" to the engine at the time, over an extended period of time the continued lack of a decent burn in the combustion chamber will cause deposits to build up on both the spark plugs and valves.

When that build up is enough to hold/maintain heat in the combustion chamber when its not supposed to have an ingnition source, it will cause pre-ignition which, yes is very damaging to an engine.

Don't go cheap on fuel, use what is recommended.

 

Update.

Appreciate the ideas but yeah going to that extreme wasn't going to work. For one yes comments about CDM's (career defining moments) weren't going to happen. For one they could just take the fuel card away. They have for others but my boss has been cool and helped keep mine so if I push too hard, it goes away completely. Also this program is all run through our fleet department.

Having said that I did send a nice note to our fleet director. Mentioned to him about the situation. Showed him a copy of the pages from the manual that recommends 93 but states a minimum of 91 octane needs to be used.

When anything other than 87 is used your tranaction comes up on an exception report. He stated that I could send him this information every time I am on the exception report for his records. I created a letter with my vehicle information, the pages from the manual and I will forward that to him every week. Really stupid that I am going to send him this every week but for me it will take a few seconds. We shall see how it goes. I bet with the hassle I lose my fuel card by the end of the year.

 

just fill it half cheap on them half highest on your dime thats what the pump does when you pump mid grade

 

I think we beat the dead horse enough already...

I would close the thread fwiw.

cheers

 

that's your opinion, glad you are not a mod

 

I'm angry with myself for adding more 'octane' to this discussion, I'm of the opinion that if the engineers that designed the engine say use it then they have more knowledge of what is required than we do. However.....
If you use Outlook for email then you can just create a signature (containing the necessary info) that's one click to pop in place when you send your monthly report to him. No big deal.

 

This topic been beaten to death and more than one place.
Closed.