Hi. I have recently purchased a 2017 clubman S automatic. My salesman and the sticker by the gas tank says minimum 89 octane fuel. I have seen some talk that I should use 93 octane fuel. What is the general consensus on the grade of gas one should use?

 

93 Octane, or if you live in CA 91.

 

From the owner's manual (this is for my '16 Clubman S, should be the same):

 

Something it doesn't mention is Top Tier only.
https://www.toptiergas.com/
Yes, it does make a difference.

 

Top tier fuel is supposed to reduce accumulation of deposits. There's a guy out there who knows a lot about fuel -- he claims one should stick with a single top tier brand/formulation for a few thousand miles and then switch to a different top tier brand for a few thousand miles, the theory being that different brands, using different additive formulations, attack deposits in different ways.

As we have come to understand it here in Southern California, where most fuel of various brands comes out of the same refineries, the fuel is "blended" at the distribution point as it's fed into the trucks for delivery to retail outlets. Supposedly Costco does its own blending at their retail outlets to control costs and assure consistent quality control.

In California, most gas stations dispense 3 grades -- with the mid grade a blend of premium and regular. And some folks throw in a gallon of E85 with a full tank of premium real gas to get the octane boost - but nobody knows for sure what bad things this might do to a MINI.

Worlds within worlds. Yes, MINIs will run on 89. But when running lower octane fuel the engine "de-tunes" itself to limit detonation/knocking from the tendency for lower octane gas to ignite too soon during the combustion cycle in the engine. Thus reduced performance resulting from the adjustments the car makes and the different ignition characteristics of lower octane fuel. Higher octane gas delays ignition and releases the power of the exploding fuel in a more optimized way. And top tier has more and better additives to keep things cleaner.

 

Actually all gasoline is the same base stock and when blending, they increase the additives to obtain the mid and preimum blends. This can be done at the refinrey or at the Spot Market facilities. If a station is within the distance the refinery will deliver to, then it's from the refinery. But many stations are outside the distance. This is where the Spot Market blends are made and delivered from there. The Spot Market facilities are blending to either the requirements of the area for that season or per the orders requirements.

I live in Tennessee now and there are no refineries with in distance to supply our stations. So the Spot Market distribution centers are used. If the Shell station wants an order, they call in their order to Shell, Shell tells the distribution center what to blend and the order goes out. Same for Chevron and so on.

The Spot Market fuel supply is from all refiners putting into this system. If you look at the system by taking away the dirt of this country, the pipe lines are like an inter state highway system. I retired from a California oil company, and we dumped in fuel like crazy (after we met allocation commitments due to contracts) since it was a guaranteed income and kept us at max production. And the other 5 refineries near us did the same.

So you could be buying Shell or Chevron or 76 or what ever fuel and get the base stock from 100 or more different refineries / companies. But blends are what is ordered at that time for that blender.

 

I would stick with the top octane that you can get. As others have mentioned your performance will be maximized and usually premium grade fuel has more additives/detergents than mid or reg grade as well. I always supplement a bottle of Chevron Techron fuel system cleaner to all my vehicles every 3000-5000 miles to help ensure things stay clean and running smoothly, YMMV.

The cost differential between premium and mid is usually not worth the worry, IMHO. Of course, right now my former Sam's Club fuel station now a Walmart fuel station only has a $0.03 difference between premium and regular (no mid), so winner, winner, chicken dinner for me! Most other stations have a $0.75 bump up to premium.

 

Here in the frozen arctic tundra, I use mid-grade (89-91) in winter and premium (93) in summer. Knock (pre-detonation) is far more prevalent in hot weather. Heck, some folks I know in Vegas even report knock problems with 93 on super hot days . Looks like you (OP) are in Florida - if I lived there I'd spring for premium year-round.

 

Life's too short to use bad gas.

 

Additives mean nothing with DI, the fuel does not wash over the intake valves.
Although, I do stick with Conoco (Union 76) There are 2 Union 76 here in the SFV, that have their prices compete with Costco.

 

Detergent gasoline does make a difference with direct injected engines, it keeps the injectors clean.

 

You may want to rethink that thought, just say'in. As Dave noted, it keeps the injectors clean and the small amount of misting that back washes into the intake port will 'marginally' help. True, not as much as a port injected system, but not nothing.

 

ARAL SUPER PLUS 102

they launched it 20 years ago for motorsport, we used it for karting, today you can buy it at any Tank station.

it contains BASF Keropur which has a cleaning effect, besides it has 102 octane, which however makes only sense if you have a tuned engine, the additive for free.

 

There is talk of making 91 the new regular, and 100 the new premium.
All about fuel economy, as higher octane burns more efficiently, but they are trying to figure out how to increase the price with people panicking.

100, is almost double out here.

 

+1 ... and 93 octane.

 

There is? Haven't read that. I don't even believe it.

It's more accurate to say that "engines that are designed for high octane fuel are more efficient." That is, engines designed for high octane fuel operate at a high compression ratio, which is much more efficient.

So to switch the world out to higher octane fuels makes no sense unless there is also a push to use higher compression engines. And while manufacturers might build and sell higher compression engines if high octane fuel were widely available, there's a bit of a chicken-and-egg problem.

In the absence of a lot of such engines, no one wants to spend more on high octane fuel that offers no benefits for them, and elected government officials certainly don't want to be seen as pushing for higher gas prices for current car owners with low compression engines, which is effectively what a switch from 87 to 91 for the base fuel would be.

 

Personally I would be a bit shocked if that is a plan anywhere within our borders. I am sure the petro companies would love to set some new revenue/profit records, but hopefully not in my lifetime.

FWIW, I usually run 100 unleaded in my weekend toy (Mustang) to ward of the detonation demons, since I really like my head gasket Around here 93 is right around $3.20/gal and 100 goes for $7.30-8.00/gal. If you buy it at the race track, I have seen it as high as $12.00/gal. Hence the reason I bring along (2) 5 gallon cans of 100 to my HPDE days, along with the fact that 4cyl only gets 6 mpg when stepping on the loud pedal.