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Old 04-08-2002, 12:12 PM   #1
willguidry
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Default can someone explain what grade of gas?

What grade of gas is best for the RS?

I have always believed if you can afford it, put the best in.
Am i wrong in this assumption?

As I have read in here that higher octane lowers your timing etc?

Is that true?

I thought the only difference was that higher octane has a higher temperature burn-off, and thusly left less deposit in the engine.

Am I wrong?

Cheers

William
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Old 04-08-2002, 12:33 PM   #2
tekriter
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Use regular gas. Do search on this, there is lots of info. Basically, the higher the AKI number the harder the gas is to burn. If you have a high compression engine (you don't) then you need a gas with a higher AKI number.

In very hot operating conditions your engine may knock. the next grade higher will stop it. I have never had this happen with subaru in 160, 000 kms. My Volvo used to knock in the summer.

Anyone that tells you your car runs better on a higher octane gas is a fool.

Different gas grades don't mix well either.
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Old 04-08-2002, 12:54 PM   #3
willguidry
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So what do I do?

I have been running 93 octane for the last couple weeks.

And have noticed actually it doesn't respond as well when I lay on the gas.

should I be running the lowest?
which is 87.

Or 89?

Will I need to go up in grad when I do mods to my car? IE intake exhaust, that kind of stuff?

Cheers

William
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Old 04-08-2002, 01:03 PM   #4
spiralsmurf
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it has been the general consensus among most people who know about car that unless you have high compression or forced induction you do not need high octane gas, even luxury cars. modern cars are equipped with knock sensors that do a good job of adjusting for different conditions. occasionally you may need it during the summer with a high mileage / higher performance engine as tekriter said. so i say unless you have a wrx go with 87 or 89.
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Old 04-08-2002, 01:15 PM   #5
willguidry
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Thanks a million Spiralsmurf!

A buddy at work just explained the knock sensor stuff to me, So I guess I'm gonna start saving me alittle cash at the pumps now.

I'll just run 89, stay safely in the middle.

Cheers

William
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Old 04-08-2002, 01:58 PM   #6
Jademonkey
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I was told very strictly I may add, but a tech at Albany Subaru, to ONLY use 87 gas on the RS. Depending on your mods though... I have a borla catback and header with ganzflow, and I get pinging once in a while, so I run 89.
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Old 04-08-2002, 02:57 PM   #7
Jack
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I use 87 normally and 93 on track days only. Octane rating is a measure of the galoline's resistance to igniting under temp and pressure. Low octane is more like a flash in the cobustion chamber....higher octane burns more slowly. Where lower octane becomes a problem is when your timing is advanced too much...then the gas explosion releases a lot of it's energy before the piston reaches tdc. A higher octane slows the flame front and so the energy release hits the piston as it just brakes over the tdc point.
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Old 04-08-2002, 04:41 PM   #8
tekriter
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well said. the owners manual says 87. It think it takes the ECU a while to adjust ot a new grade as well. I try to get good quality gas from the same place as much as possible.
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Old 04-08-2002, 05:20 PM   #9
Jaxx
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Old 04-08-2002, 05:25 PM   #10
SoCalScooby
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Talking

I love this board, everyone is so helpful

~Eric
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Old 04-08-2002, 10:10 PM   #11
dsc
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Quote:
Originally posted by tekriter
Anyone that tells you your car runs better on a higher octane gas is a fool.
Now there's a persuasive argument.
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Old 04-08-2002, 10:18 PM   #12
Jademonkey
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Haha...my car definately runs better on 89 than 87. I get slightly more MPG on 89. I ran a tank of each for 2 weeks, after I put on my last mod, taking note of the mpg for the last week for each octane lvl. It's slightly higher...not by much though.
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Old 04-09-2002, 12:45 AM   #13
willguidry
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Yeah, I've been doing 93 Mobil1 gas.

I'm going to switch back down to 89

You guys are awesome, I love learning this stuff from people who know.

Cheers

William
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Old 04-09-2002, 06:13 AM   #14
hobun2
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Question

I've been using 94 octane for the past 6 years on all my cars. Actually, I used 87, then 89, then 91 and then 94 on my second car, 1989 Tracer.

There reason I switched to higher grades was that I was able to gt better gas mileage for a similar price. Also, it seemed that I got better acceleration expecially in low RPM.

I've been using 94 since I bought my MY93 L. Do you guys recommend I switch to a lower grade?
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Old 04-09-2002, 06:17 AM   #15
hobun2
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Default Japan

If I remember correctly, they have 98 octane gas in gas stations inthe UK. I think a client of mine told me that a few weeks ago...
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Old 04-09-2002, 08:21 AM   #16
tekriter
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