anyone chime in .... state your opinions if your not sure ...

 

I always use 91 octane fuel in my 01 Zetec and my car sounds and runs better than any other Zetec running 87 octane (10%) ethanol. I think its load of crap that it damages the engine.

 

Uh well I run 86 octane in my 08 and she runs great. Here in El Paso, we have 86, 88, and 91, very crappy gas compared to what I am used to on the East Coast in MD.

 

It really only costs more. If your car isn't modded in any extreme way then it will be fine on 87 I personally run 89 in my car because I notice slightly better economy and smoother idle. I ran 93 once for giggles and noticed no change from 89. Really whatever the manufacturer recommends is best.

 

thanks for posting ur response guys, im thinking of running 93 instead of 87 becuase its cleaner has fewer particles and preforms better... its just weird to me that the manufacturer approves of 87 , although they don't bluntly say do not use anything over 87, but they do bluntly say don't use anything lower... dont want to damage the fuel system so im unsure

 

Technically 93 octane is less flammable.It is more stable at higher pressures and wont burn as efficiently as lower octane. It can be minimally noticeable sometimes. 93 doesnt mean it cleaner either. If the tanks the fuel is stored in are shity then the gas will be dirty. You wont damage the fuel system either.

 

i appreciate the info !

 

np glad i could help

 

They specify the octane given the compression ratio of the engine. If youre having issues with knocking for example, something like 91 or 93 may very well fix that and youll notice it runs better.

I know someone will claim better mileage.... Maybe they did have it after switching. Maybe they had knocking beore and it fixed it.

Personally for me, using 91 octane resulted in an average of about id say 2-3mpg decrease, however i kept using it as it was the only fuel that kept the mil light from coming on and giving a code for fuel level sensor malfunction (why that is beyond me)
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mike so i guess you were using 87 before you made the switch??? another thing the manual actually says if you have knocking or trouble starting and so on, using a higher grade may cuase these problems to be more pronounced?? go figure lol.... im actually waiting for the tank to go on E then im adding chevron fuel injector cleaner and filling it up right after with 91 to see what happens

 

lol wtf. Maybe theyre saying it could make it worse by igniting too late. And no actually ive always used 86 and it ran strong. The kind of knock i was talking about was detonation.... Igniting too early.
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right i see what you mean, so in closing is it safe to say using higher octane gas will not damage the fuel system ?? even if the recommended level is a lower octane

 

i would say it depends on how the engine is running.
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It shouldnt ever damage the fuel system. The only risk you could run it starting to dump unburnt fuel into the cat, which in turn can ruin than. That would be an extreme circumstance though.

 

It's all about the burn. I frequently advise people to purchase spark plugs that are one step colder, this reduces "spark knock" that seems to be more of a problem now that manufacturers are trying to get the most power out of their engines on low octane fuel without making those engines larger. We're really running our engines right to the edge of what's possible with the fuel, and is seems to me that the test fuel used by manufacturers is not the same as what we have all around the country.

Anyway, you can reduce spark knock one of 2 ways- increase octane, or decrease spark plug heat range. What you want to figure out is what is most economical for you. I would run 2-3 tanks of each fuel keeping track of your FE and fuel cost during this time. Look not for mpg, but miles per dollar. If spending the extra $2 per tank on premium fuel costs the same or less than running 87, then that's the route I'd go.

Really, the premium fuel is much better as far as crud- from the fuel blender. However, there's always the tanks at the station that can cause problems. I'd also recommend- to everyone- to test all the brands of fuels within reach of your usual travel route to see which one of those gives you the best mpd. Sometimes you can find up to 3 mpg difference between fuel brands, so it's worth investigating. I wouldn't go too far from your typical route for fuel- not because it will burn up fuel, but because it's just too much of a PITA. You want to find convenient + cost effective if it's going to be cost effective at all. For me, P66 fuel is best, but there is not one in my local route, so 2nd best is Kroger. I am lazy to my own suggestions though, and haven't tried Kroger 93 to see if it's cost effective, but I have colder plugs- so probably not.

 

"WHYNOT" i was waiting for you to find this thread haha , thanks for your input educational as always ! I see what your saying, i will compare a couple national brands and octane levels and see what happens...although i dont have any knocks present, just catious of damaging my fuel system by using gas that is not recommended

 

It's not that your damaging it- spark knock happens sometimes even if everything you can possibly do within reason is correct. Fuels are imperfect- whether premium or not. Manufacturers used to "dumb" down the engines to be sure that you'd get consistent, even if completely inefficient, running. This meant spark retard to the point where knock would be much less likely, but that reduces power. Now they run things up to the edge getting every possible smidgen of power. When you run, even for a few seconds, a much less than perfect run of fuel, the sensors will sense the knock, spark timing is retarded and more fuel is added to the A/F mix to alleviate spark. This means less power, and more fuel used. Within a short time, the controls allow the spark to be returned to it's normal map until you run into imperfect fuel again.

It's our understanding that low grade fuels with stock plugs tend to reduce mileage through computer controls to limit spark knock to the point where you're better off with colder plugs or premium fuels in most cases.

You're not going to blow anything up- don't worry about that at all. The only way you're going to experience the "detonation death" of an engine is to have modified it internally to the point where what would be a stumbling block for a stock engine becomes death to yours. You can't even go that far without adding a turbo or high compression pistons. Air intakes and exhausts don't hurt anything. I doubt you could even lean out your A/F ratio enough with a flash programmer to damage the engine.

 

This has all you want to know and a lot more. Its a good read and worth your time to at least skim it

Changes in Gasoline Manual IV

 

cool thanks fellow hatcher