[deliriousga]

I just use Chevron w/ Techron always in the 928. No additives necessary. The wife will put other gas in the Boxster and I do have to use a cleaner (Lucas injector cleaner) about once every 6 months to keep hers clean.

Originally Posted by MNBoxster

Don't make the mistake of equating Octane with Power. High Octane Gasoline does not necessarilty have any more power, in fact, depending on the Octane Boosting Agent used, it could actually have less Power.

Thanks Jim for pointing out the biggest misconception about octane. Most people (including myself until about a year ago) equate high octane with explosive power, but it's the opposite. The higher the octane, the lower the volatility. That's why you generally get better gas mileage from higher octane gas....if the car is made for that higher octane.

Originally Posted by blinkwatt

Could the boost that the toluene affect the catalayic converter in any way?

Toluone in effect "waters down" the gas to make it higher octane, so I think it would be the opposite (lower octane being the problem), and not affect the cats, but could harm the O2 sensors. Lower octane gases combust at lower compression, so in the Boxster they would combust early, sometimes before the spark and before all of the gas has been injected into the cylinder. The problem is when gasoline combusts early, not all of it burns so you have gas rolling down the cats and into the O2 sensors. That creates a cat fire risk and is the reason the manual says not to let the car sit and idle/warm up. The computer will adjust for it, but it's not optimal for the Boxster and it can only adjust so far. If you've chipped it, the computer does not adjust for lower octane gas.

Conversely, if you raise the octane too high, then the compression may not be high enough to ignite the gas efficiently when the spark occurs. At that point, you're just wasting your money since really high octane gas is mucho $$$ and you're not gaining anything from it.