Had a stupid moment. Actually, I am so used to filling up our primary family vehicle with regular fuel that I am chalking up to muscle memory.

What do I do now that I have a full tank of regular fuel in the mini? Is it going to hurt the car if it only happened this once? I obviously would not do this again, nor did I plan it to save $1 -$2.

 

Its not goint to hurt the car.

They only "Recommend" using high octane fuel. It is NOT required.

I have run regular, mid grade and premium at different times to check gas mileages over 7-8 tanks each and found that regular actually gives me the bets mileage. My car now has 97K+ miles on it and runs regular all the time now with no problems. Only parts replaced on my car were the HPFP and the thermostat housing, neither of those because of the fuel I was running.

 

Drive her easy and you will be fine. My sister has a leased s and runs 87 and has 14000mi. I would not want to be the person that buys her mini when she turns it back in.

 

Pour in a can of STP Gas Treatment, or any of the other Octane-based Gas Treatments. That should remedy the inadvertent accidental fueling.

Octane needs to be at or above the recommended level to avoid knocking and backfire, which can damage an engine. Your car has anti-knock protection to avoid catastrophic detonation. It automatically retards the timing with low octane fuel but it may effect the way the car accelerates, your mileage per gallon and the longevity of the engine block and other parts such as the heads, pistons, fuel injectors and manifold if you were to use such low octane fuel for any substantial period of time

 

Just drive it carefully for this tank...no hard acceleration.

They ping even on 91 octane...so I'd hate to see it with 87.

You can try a can of octane booster, but those don't do much. If you are really concerned you can find a pump with 100 octane around you (if there are any) and mix in some of that once you tank goes down a little bit.

I'm assuming you have an S? If its justacooper....then don't worry much at all.

 

It is not a big deal. I know owners who have NEVER once put premium in their car. The computer will do its job and retard the timing and you won't get as good gas milage as you do normally.

 

I don't think it matters at all. If money were a problem for me I'd use 87 too, and see how it ran.

 

Your, fine :-)

 

Not a problem at all. You may decide to do it more often.

 

Regular will work...but don't try diesel. That's really the WRONG fuel.

 

that would cause a HUGE problem!

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Thanks for the updates. I assumed that it wouldn't cause a problem, but figured I would get more opinions.

 

one thing that helps

understand what OCTANE means . . .

for example - did you know that is is HARDER to ignite a higher octane fuel?

 

I don't yet own a mini but I have never quite believed the manufacturer recommendations on fuel. More and more they all seem to "recommend" the higher octane but I find it makes no difference to gas mileage, performance or longevity of the car. This is based primarily on my experience with Hondas and Acuras, most of which say "premium fuel only". Does anyone really think it makes a difference in your mini (aka real experience vs. manufacturer recommendations)?

Thanks in advance for your thoughts on this!

 

Yes...search and read.

 

As a noted MINI technical guru mentioned at MITO last year--(for every penney you save using fuel less than 91 octane you will spend later on additional maintenance). Until I see evidence to the contrary from MINI I will continue to follow their recommendations.

 

Got it. Did the search/read. Most of the information makes sense. As I said, I have always ignored this on my Honda's but I get the scientific explanation of why it might matter in the long run if you continually use a lower grade on a car that expects premium. I'll probably go ahead and do the premium thing when I get my roadster. Thanks.

 

As others have mentioned, using the lower rated fuel isn't the end of the world, but just isn't worth it...the car's ecu will retard timing as someone posted above, and it'll prevent knock, but lower performance/gas mileage. As someone else posted, the lower octane fuel is easier to ignite, so it's igniting earlier in the combustion cycle than when it normally should. When you actually calculate it out, would that really be worth it. Let's figure premium vs regular fuel is $0.10/gallon. With a 13.2 gallon tank in a MINI, you're looking at $1.32 extra per tank. Fill in up once a week for 12 months and you're paying about $64 a year more for better gas mileage. Is it really that big an expense considering the cost of the car?

As for Honda products, they have actually done very little to update their engines in some time (why I couldn't tell you). They have not moved to direct injection and with their higher performance products, they have some high-pressure fuel injectors with small openings that tend to clog when using the lower grade fuel which has fewer detergents than 91 or 93 octane fuel. Made that mistake myself and had to pay quite a bit to get them cleaned out on an old CL Type-S.

 

I did the same thing. My 2012 MCS made strange grinding noises when at start idle. It ran well though. When I got back to premium, normal. I dont think it likes regular octane.