Re: Digest Number 870

[Sally Carroll]

Did anyone beside me notice that standard unleaded in GB is rated at 95 octane? We can't buy anything other than our suppliers 87, 89, 92or 93 octanes. No wonder our fuel is cheaper. . . . .HA HA HA. With variance of price 10% or more each week I try to stock all my fleet and mowers as well when the price breaks below the $1.30 barrier for regular. But really, will not the higher octane cause problems? Or is higher better even if not supercharged? And does someone have a chart to tell us which is preferable? There was a story circulating recently about the pool gas(from WWII years) and its undependable octane. I did a self test some years back (when regular was 29 cents) and discovered that my Volvo B18 engine delivered a slight better performance and slightly better mileage. End result of 'test' the cost per mile was identical, whatever the grade but slightly smoother on high test.. . . . Sally

[Chip Old]

On Sat, 8 Jun 2002, SALLY CARROLL wrote:

> Did anyone beside me notice that standard unleaded in GB is rated at 95 > octane? We can't buy anything other than our suppliers 87, 89, 92or 93 > octanes. No wonder our fuel is cheaper. . . . .HA HA HA.

The difference may in the way the octane rating is calculated. In the US since the late 1970s we've used the "(R+M)/2" (or "pump octane") method, where "R" is the Research Octane Number and "M" is the Motor Octane Number. Given the same gasoline, its RON rating is usually higher than its MON rating. Prior to adoption of the "pump octane" system, the advertised octane of gasoline was usually its RON number. That's why premium grade gasoline that used to be rated at around 100 octane is now rated at about 93. Perhaps one of our list members in the UK can tell us what rating system is used there.

> With variance of price 10% or more each week I try to stock all my fleet > and mowers as well when the price breaks below the $1.30 barrier for > regular. But really, will not the higher octane cause problems? Or is > higher better even if not supercharged? And does someone have a chart > to tell us which is preferable?

You need an octane rating high enough to prevent the engine from knocking. Using a higher octane than that is just a waste of money. -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E fold@bcpl.net