[2one3E90]

Ive had 100 octane in my tank for a 3 days now. Still 3/4ths left. Its alot but my coworker is saying it can hurt o rings and stuff. Also I notice my gas tank fluctuate around the same area. Should I burn it off as fast as possible? Thanks

[Fritzer]

It's not going to do anything except adjust timing to the octane level and run as if you put 93 or 91 in it. It just burns cleaner, no tangible performance benefit unless you are specifically tuned to identify and run on 100 octane fuel - and it certainly won't damage your engine.

[Brian86]

No harm.

And it smells like the race track

I'd be surprised if the spark timing map for US cars has any values beyond what '93 can provide. And obviously it isn't possible to change the compression ratio, that's where the real power gains come from.

[lookalikehuuh]

I assume your friend has been smoking some stuff because where the hell did he learn that high octane damages o-rings?

All high octane does is have better resistance to pre-detonation for high compression engines allowing properly tuned ECUs to add more timing and therefore produce more power. In boosted engines it allows you to raise the boost easily without significant timing corrections.

Question, so you filled up with 100 octane gasoline, doesn't that cost like $10/gal so I presume a full tank cost you well in excess of $150 for a car that isn't tuned for it? If you want to burn some money just go ahead and write me a check and drop it off at my house ill put it to better use :P