Downgrading from V-Power 99 octane to 95 octane..

[Bo525i]

fixes all my stuttering problems, does that make any sense?

I find it hard to believe that a higher octane gas would cause stuttering, but thats exactly what I get, odd huh?

[ryan roopnarine]

the lower the number, the higher the energy per unit of gasoline, generally speaking. i don't know why that would stop studdering, i would think that maybe the tank at your gas station is feeding crud into your car?

[Bo525i]

Its not the gas-station I use several different Shells for the V-Power.. It just doesn´t make sense tho if it was crud it would pass thru even with the lower octane at least at first..

Scenario is: I put lets say 20l of V-Power and as soon as I hit around 2000rpm I get this hesitation/stutter, then immediately after, at almost empty I fill up with 20l of 95 octane and the hesitation/stutter is gone.. Its freakin me! :)
I´ve done this 3 times in a row now with the same results even with varying amounts of gas of both sorts.

[Bo525i]

I guess I should be glad actually as the 95 is far cheaper than the 99.. Its just the mystery of it thats buggin me! ;)

I found this on the subject:


Octane Facts
• Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle
because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored
since it can result in serious damage to the engine.

• High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when
cylinder pressures are high.

• If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in
switching to higher octane gasoline.

• If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could
be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a
high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.

• Almost all of today’s new cars have fuel-injected engines that need to use gasoline with a detergent additive.
They do not necessarily need high octane gasoline with a detergent additive. Generally, new automobiles
need high octane gasoline only if the manufacturer recommends it.

• Always follow the auto manufacturer’s octane recommendations in your owner’s manual.


Octane Myths

• High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve
mileage. If switching to high octane gasoline does improve mileage, you might find that your engine, or its
control systems, need repair.

• High octane gasoline gives quicker starting.
No, it doesn’t.

• High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn’t notice any more power on high octane
gasoline. Again, if it does make a noticeable difference, your engine, or the engine’s electronic control
systems, may need repair.

• High octane gasoline has been refined more – it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not necessarily
make the gasoline a “better” product for all engines. They just yield a different blend of hydrocarbons that
burn more slowly. The additional steps also increase the price

[Dave M]

M50 engine (high mileage), always run on 87 or 89 with no trouble. I used to believe the hype, but have since believed in what works

Dave

[Bo525i]

I ran vpower in my M50 due to the chip I had in with very good results, so I automatically just thought that it was as good for the M60.. But not!