I know that is sort of a primitive question, but I've gotta ask.
I just bought a 2004 WRX. Dealer tells me that I should use at least 89 octane gas. Is this BS?? If not, what are pros and cons of using higher ocatane gas??

Use 91 or 93 octane gas, honestly. You can get by with 89 if you're cheap. I'm too tired to get into the details tonight, but it honestly is worth a few extra bucks every fill-up.

Not to sound sarcastic, but did you open the glove box on your car?
There should be an owner's manual in there, there is a section in the owner's manual that covers what gas you should use and everything.

If the minimum octane you should use is just that, the minimum, you can use anything of a higher grade without a problem.

Well Yes, the owner's manual says to use at least 91 for WRX, and at least 94 for WRX STI....

and I know how this octane stuff works, with delayed combustion and everything.

What I read consistently is that if your engine doesn't "knock" or "ping" with lower octane, then any higher octane gas is a waste of your money.

Having said that, I've driven with 87 and 89 and I don't think I've heard any knocking or pinging. ONLY porblem is that I've never heard a "knock" or "ping", so I'm not sure what they sound like....CAN Anyone describe that for me???

Hard to describe without using their names, but if your engine knocks or pings, you'll know it. I'm gonna say this again: sure your car will run (fine) with lower octane gas, but for the life of your new car, it's worth paying a few extra bucks. Honestly. I've been putting 93 octane gas in that 92 Volvo as long as I (and my family) have owned it, and it still runs like a champ. The turbo's still clean, lubed and responsive, everything fires as it should, and I've never pinged or knocked.

Use the proper octane fuel.

Hard to describe without using their names, but if your engine knocks or pings, you'll know it. I'm gonna say this again: sure your car will run (fine) with lower octane gas, but for the life of your new car, it's worth paying a few extra bucks. Honestly. I've been putting 93 octane gas in that 92 Volvo as long as I (and my family) have owned it, and it still runs like a champ. The turbo's still clean, lubed and responsive, everything fires as it should, and I've never pinged or knocked.

Use the proper octane fuel.

---Sounds good to me. Thanks man.

higher octane fuels burn harder, faster, hotter, and cleaner they are an overall better choice. you wont suffer from carbon buildup with high octane you get a slight power increase and it helps your emissions a bit aswell due to the hotter cleaner flame. right now im running my impreza l 2.2L on 93 octane.

After reading this post, I might have to re-think about buying an STI in a year or so. See, I live in CA where most of the time the highest we get is 91 :banghead:

I really want an STI too, but it's hard to find 93+ anymore. I'll have to settle with a WRX with 91 octane. My friend has one and he uses 91 and runs great.

i woulndt change your choice of cars over 2 octane. just get the highest you cnan get. im sure that the sti will run on 91 octane just fine it just runs better on 93. i realy doubt that its going to hurt it that much 91 is still quite high.

An STi will run fine on 91 octane gas. You have nothing to worry about. Just don't be cheap and buy anything less than 91.

Okay then, thanks for reassuring me. I can't wait to have an STi. It's the best buy for under $33k :grinyes: , IMO

And there have been a few cars that tried to tempt me into forgetting about it, but they have come and gone.

And I shouldn't really stress about not having 93+ or higher, cause I know some places that them, it's just really out of the way.

for all intensive purposes, 91 = 93. Yes, they're different, but basic daily driving, your car won't notice a difference.

And I wouldn't go and say that the STi is the best for 33k... The EVO continues to edge it out. I know we could go on all day about this, and I'm not trying to convince you, but test drive both. I've driven both, and the EVO feels great. Most magazines put it ahead of the STi as well.

Just a personal opinion, so it carries no weight. Just be sure you test drive both.

higher octane fuels burn harder, faster, hotter, and cleaner

this is not true... higher octane gas burns slower, the reason higher octane gas helps get rid of pinging is because it does NOT burn as fast, so lets say you have a lot of carbon in your combustion chamber... when the carbon gets hot in there it will start to ignite a lower octane gas faster than it would higher octane, so when you run higher octane you allow the engine to burn the gas when the time is right, not as soon as it touches the hot carbon

make sense?

and by the way, technically lower octane gas would make more power because it burns faster... the thing is the difference is so small it would be very hard to notice and most high performance engines can't really handle low octane anyway