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Premium fuel in mini coopers

is it really necessary

YES! A Mini Cooper is not an economy car, but a funny looking BMW with the high BMW cost of ownership. Read your owner’s manual and do what it says.

If you are concerned about the $3 extra per fillup vs regular. You are in for a rude awakening in car ownership costs.

$3?
With as small a tank as those things come with(10 for the normal and 13 for the S), it wouldn’t even be THAT much, even if they ran the tank dry.

The price difference is $.20 per gallon, which is $2 per 10 gallons. The price difference is negligible compared to what you could end up doing to an engine that requires premium fuel when you use regular in it. As stated before, a Mini is a funky BMW with BMW cost of ownership. If you want an economy car with a low cost of ownership that will use 87 octane, buy a Hyundai Accent.

Regarding the option of switching to regular, this will lead to the dilemma stated in the Fram commercials from a few years ago. “Pay a little more now, or pay a lot later.” A whole lot later, and later may come much sooner than you want it to.

Check your owner’s manual. Chances are it will say that it requires premium. That would mean you use premium or risk serious engine damage. If it says recommends premium, then failure to use premium will decrease you mileage and power so all you will be doing is decreasing power from your car without reason.

It’s like a buck or two extra per fill up to use premium? And the car probably gets around 30MPG?

Just fill it with what it needs!

If you don’t want to buy high octane fuel, don’t buy a car that uses high octane fuel. Do your research first, and buy a car you can afford to drive. A car you can’t afford to drive is nothing more than an expensive piece of modern art.

In Texas the difference is $.30/gallon, but the advice still stands - Minis are fast, fun little cars because of their highly tuned engines. Use premium.

No, it’s no more necessary than oil changes and other required maintenance.
However, the least expensive thing (in the long term) for you to do is to use 91+ octane gasoline and do all the correct maintenance as it is required.

Why do so many people think the manufacturers lie in the owners manual?

Do we even know the OP own’s the car in question? Maybe he/she is considering buying one. At least that’s what I hope.

it’s not just the Mini, it’s the S (is that still supercharged, or is it turbo now?) in either case, the compression is higher, so the higher octane is necessary, as opposed to putting it in a car that doesn’t need it = waste

“Why do so many people think the manufacturers lie in the owners manual?”

They do occasionally:
‘Lifetime’ fluids, 105,000 mile valve lash adjustment…

Because the oil companies pay them to lie…92 is “high octane”??? High begins at 100 octane.

Actually the preheating of the mixture due to the supercharger or turbo can cause preignition, but the actual compression ratio is usually lower on a turbo engine than a normally aspirated one.

The compression ratio may not be higher, but the compression is.

The compression ratio is the simple mechanical number, the cylinder volume at TDC divided into the chamber volume at the bottom of the stroke. The compression, the pressure at TDC, increases as more volume is pumped into the cylinder. The higher the pressure of the fluid (air is a fluid) entering the chamber, the higher the pressure will get inside the chamber.

And that pressurization from the turbo or supercharger elevated its temperatures too. And I’m sure a turbocharger transfers heat from the exhaust into the instream too. Hence the intercooler.

I think the issue is the stigma carried by owning a car that requires preminum, something like “you bought a “little” car (thinking econo-box) that requires preminum”? “boy you sure don’t know how to shop” something of an embarassment issue that can’t be put to bed no matter how well you explain.