ResQman

So I have stock 06 Mustang GT. I normally run 87 Octane with the occasional 91 octane tank. The car runs great. No Tuning other than the factory standard tune.

The other day I decide to put in 94 Octane in. Now, I have a bit of roughness in the engine. Not bad, but just a little bit. The gas is from a reputable station and so I don't think there is a water problem here.

Opinions?

Art161

Yes. You should follow the manufacturer's recommendation for a stock tune, or a custom tune should be designed for a specific octane.

Orion_240

you are not only wasting money throwing in high test in a stock Mustang, but you could be causing engine troubles. High octane gas is great in high compression engines... which you don't have.

Fill it back up with the cheap stuff and thank God you don't live here, where premium is almost $4/ gallon! That would be an expensive lesson.

mygt500

like the others have said get what the tune or manufacturer recommends and no more......save the money for mods!

S281 E

When I first started with my first car I too was guilty of doing the same thing. UNtil you read it or someone tells you its hard to convince yourself not to put the higher octane. Just save your money and use the 87. Think of it this way. If Ford recommends it than they must have done their testing with it so its been proven to last.

rfm678

Higher octane gas is needed for high compression engines, as said before^^^ we don't have one. When a fuel/air mixture is compressed enough it will detonate even without a spark, the higher the octane the higher compression it can withstand. Running high octane in our stock engines may cause incomplete detonation resulting in the loss of power and roughness you are feeling. Not to mention the possible damage to the emissions system and cats from the residual fuel. Just stick with the cheap stuff and you'll be fine, if you want better performance get a tune.

Goldenpony

Just a possible waste of money. High octane fuel will not harm your car.

157dB

Is there such a thing as TOO much Octane?
Not if you dont wasting $$ for no performance or drivability...

breathegood

Which can lead to carbon buildup, hotspots, and pre-ignition (pinging, or spark knock).

Run only as high an octane as you need to to prevent detonation. This goes for any car, not just Mustangs.

ResQman

Here I paid $1.029/Litre...multiply that by 4.5 (thereare 4.5 litres in 1 U.S. Gallon) that makes it $4.63 CDN which work out to $4.34 USD / gallon.

I will save my money and run 87 Octane.