On Fri, 23 Apr 2004 21:58:30 +0200, "Friedrich Ostertag"
wrote:

Hi Gord,

Well, just a comment about domestic automobiles, I didn't mean to
indicate that I operate them below the manufacturers specified
octane ratings, after all, I believe that the manufacturer knows
his engine best and I'd never try to second guess him, but I have
all kinds of friends and relatives who use hi octane fuel in
their cars even though low octane is recommended. (complete waste
I feel)

Ah, you're absolutely right there! Sorry for the misunderstanding.
There is no point in using higher octane than what the engine was
designed for. Even knock control will not advance ignition beyond the
calibrated map for the designated fuel.

However a lot of people over here fell for a marketing trick of Shell
Oil: Instead of the 98 octane highest grade fuel sold in Germany and
most euroean countries they offered a 100 octane (by the way, this is
ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly
all kinds of mysterious additives at 10 ct / Liter premium over other
oil company's 98 octane. Lots of car magazines and also the ADAC (your
AA) tested it in various models and found no difference whatsoever in
power and consumption. Yet Shell sells 10% of it's turnout in V-Power
while the other's only sell 5% 98. Talk about snake oil...

Definitely agree with you there ... The Puma that I have has a
reaction to the higher octane 98 RON Optimax fuel that Shell sell over
here.

It's not a good reaction, like increased power or economy, it's a bad
one. The bad reaction takes the shape of the engine management
struggling for the first couple of miles to get used to the differing
octane rating. Symptoms included poor running including reluctance to
idle. I suspect that the anti-knock control was self adjusting itself
for the increased octane rating. It also takes a little while to get
used to 95 RON unleaded when that goes back in.

Anyway, no measurable economy improvement (I nerdishly track my mpg)
and no perceptible power improvement. Although other people reckon
they see power improvements with other cars.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)