USA Octane rating query

sntee · Post by **sntee** » 24 Oct 2006, 14:55

I've read a few postings now that refer to "Premium" fuel as having 92 octane.

Is this the top octane rating available in the states?

In the UK our standard Unleaded is rated as 95. You can also get Super Unleaded at 97 and Shell have just upped their "V-Power" fuel to 99 octane.

Does the engine management system automatically compensate for different octane ratings?

If not, how can the car produce similar performance levels regardless of fuel?

sntee · Post by **sntee** » 24 Oct 2006, 15:06

Dependant on the responses to this post, I might start a poll.

Just to see if we can establish once and for all whether higher octane fuels are worth the expense.

I regularly drive 4 miles out of my way to go to the nearest Shell station to buy V Power, but if I'm honest, I can't say that the difference between this and regular 95 octane is so significant.

Post by **billofdurham** » 24 Oct 2006, 15:56

Both Shell and BP plug the 'super' fuels by saying you should get 28 - 30 miles more per tankful. Well, big deal. If you are going out of your way to buy this stuff, in my opinion, you are burning money.

My 850 runs happily on basic (95 octane) fuel and returns, on average, 30mpg. The super unleaded was introduced for older cars which would have been running on a mixture of leaded and unleaded, so really, for our cars, that is a waste of money too.

That's my two-pennorth (two cents in the US), so if you run a poll put me down for the cheapest.

Bill.

White850Turbo · Post by **White850Turbo** » 24 Oct 2006, 19:15

Octane is calculated differently in the states than everywhere else for some reason. Here, we use an average of the RON (Research octane number) and the MON (Motor Octane Number), as where everywhere else just uses the RON rating.

In the western third of the country, the highest octane fuel available is 91, but most places east of that have either 93 or 94. Some stations in the midwest and east coast even have 100 octane available at a premium price.

So, you can't really compare the two just using the numbers.

Post by **MadeInJapan** » 24 Oct 2006, 19:39

The best I can get is 94 where I live unless I make a trip out to the airport.

Post by **hausmeister** » 25 Oct 2006, 01:59

http://en.wikipedia.org/wiki/Octane_rating

87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe.

EJVolvo · Post by **EJVolvo** » 25 Oct 2006, 07:08

Another issue to consider in pricing gas is the level of detergent in different gasolines. In USA I believe that Shell is one of a group of dealers that offers increased levels of detergent, as compared to other brands....I think V-Power, for example, has 5X the minimum required (by law) amount of detergent. You may pay more, but more detergent=cleaner engine=longer life.

Black850 · Post by **Black850** » 26 Oct 2006, 16:28

Modern cars have computers which adjust the timing of the car if you use lower grade octane. It doesn't hurt the engine or anything, the car just doesn't produce its max performance. So you're not gonna hit the top horsepower ratings and acceleration ratings and so forth.