posted 09-02-2003 01:51 AM                       

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What is the difference between regular, mid-grade and premium in the US? Here we have normal unleaded (95 RON) and super unleaded (98 RON). There is also 'Lead Replacement Petrol' (LRP), which is 98 RON but with a synthetic compound added for use in older cars which still have soft valve seats (lead in petrol is now illegal under European Union law). Normal unleaded is the equivalent of $1.15-20 per litre and Diesel around $1.20-25, while super and LRP are $1.30 plus.

I don't know what proportion of petrol engined cars used super. I would guess it's quite small, because I certainly don't know anyone whose car needs it.

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Gasoline at US stations is available usually in grades of 87 octane, 89 octane, & 91 octane. Some stations' premium is 93 octane.

Leaded gasoline has not been available in the US since the early 80s or late 70s, when its distribution was phased out for environmental reasons. When leaded gasoline was phased out, there was a large uproar among the antique/special interest autombile groups who worried about the damage to their valves & valve seats due to the loss of the tetraethyl lead. Many, many entrepeneurs came out with additives to put in gasoline to protect the car, increase octane, etc. - none of the additives could contain actual tetraethyl lead of course, that would be illegal. You will likely be pelted with many, many images of dirty-looking automobile parts contrasted with nicer ones captioned "SEE THE EFFECTS OF UNLEADED GAS!" In the long run, in normal use, unleaded gas made no difference. In modern cars, I'm sure that the ones mfd for sale in the UK are likely to have heads that will be long-lived when sold in the US.

Modern cars in the US are all fuel-injected, have electronic ignition, & are microprocessor controlled with a bazillion sensors all over. If pre-ignition is detected, fuel mixture and ignition advance can be adjusted. Have you noticed that you almost never hear a backfire anymore? There is less power, but the driver usually does not notice & the car is not damaged. No modern car really "needs" it, but it does have an affect performance.

The last caburetted car sold in the US was the unjustly maligned Yugo. It's drawback was that it was so inexpensive that folks just flogged them until they needed repair, & then found the repair was for more costly than the car! It made the car seem disposable, & thus it also became unfashionable & undesirable. It was quite a nice little urban car, except that the manual transmission felt like stirring with a stick. Early ones were infamous for a problem which plaqued many cars of the early catalytic converter era - they'd clog up & just stop. Again, the repair would cost almost as much as for what you could buy another!

posted 09-03-2003 03:19 PM                    

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Gasoline at US stations is available usually in grades of 87 octane, 89 octane, & 91 octane. Some stations' premium is 93 octane.

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