Premium unleaded

I use the octane Ford recommends--87. Ford says not to use premium gasoline in cars that are designed to run on regular.

using a higher octane once in a while will never hurt. probably more helpful.. the hotter burn would probably clean out the cylinders that little extra bit.

if your set on running a higher octane, run your local 89, or go pickup a tuner and program it for 91 or 94

Art161 said:

I use the octane Ford recommends--87. Ford says not to use premium gasoline in cars that are designed to run on regular.

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So if you get a tuner and tell your car to run on 93....then the engine essentially WANTS to run on 93 now, even though Ford designed it to run on 87?

So is that still safe? I use 87 octane as my car is bone stock (for now).

wants too? more so of Needs to.. the tuner will be changing all the fuel and ignition timings to compensate for the higher octane fuel.. if you put a lower octane with the tune in. You'll have engine knock... essentially pre-detonation of the air/fuel before the spark plug ignites it..

and engine knock is baaaad!

I find that 87 is just fine, but some of the cheaper places like Wawa(philly area) tend to produce too much spark knock.

If I'm in a jam ... I get 93 octane from there.

They have great food and coffee there, but their gas really sucks!

Snooze said:

using a higher octane once in a while will never hurt. probably more helpful.. the hotter burn would probably clean out the cylinders that little extra bit.

if your set on running a higher octane, run your local 89, or go pickup a tuner and program it for 91 or 94

Click to expand...

Actually, the reverse is true. Using premium fuel actually produces a slower burn. It doesn't hurt to use premium in an engine that has been tuned for 87-octane, but you'll gain little or nothing in the way of performance.
Regular vs Premium

Gas

I have run 93 octane about all of my car's life, 40K miles. I ran it before and since I installed my Brenspeed tune. Car has always run great.
Our cars have knock sensors and within their range will adjust timing so it is always just under where spark knock will happen. I have read several places that by running higher octane, your engine will make a LITTLE more power, not much but a few HP. Is this enough to justify the difference in price? That's up to you.

I would love to know where the myth that high octane fuel is somehow going to somehow hurt engines, sorry but this just isn't true. When your manual tells you to run 87 octane, all that means is it will run on it. A lot of people don't want to spend the money for the more expensive fuel, and that's fine, but using it will not hurt anything - period. Premium fuel has more detergents and will help the injectors and intake track cleaner. Gasoline has never cost more or been of such low quality, so $4 extra per tank in a performance car doesn't bother me. I've always noticed that even in a low performance car, when I use premium, the engine just plain runs better, even idles better. V-Power for me. Just my $.02.

I shift back and forth with 87 and 89 octane of Shell gas on each tank fill up...no more spark knock and she seems to run beautifully!

Running 87 in my older 2000 GT would produce engine knock. 89 solved it.
On my new 08 GT, 87 works perfectly.
I have a buddy who used 91 in his 07 GT, and there was no difference at all.
You're just boosting oil company profits, which is good because I own stock...

Not to hijack the thread but...what effect does rust have on octane? I got some gas the other day that was very rusty and I swear my truck is running worse for it.