Premium gas, or?

[ill86]

Detonation is most likely to occur near peak torque when cylinder pressures are at their highest.. Which, because of it's fairly flat torque curve is 143 lb-ft from 2,800 rpm all the way through to 6,500...



Knowing these points you can see why it's not good to run less than recommended octane. It is 12.5:1 CR ... Which is pretty high for a production motor.

[DeeezNuuuts83]

I don't understand why people even think about running less than premium octane on any performance-oriented car. It's only a 20 cent difference per gallon. If you drive 12,000 miles a year, it might save you around $100 in gas, which isn't worth the risk of detonation while likely being outweighed by the cost of tuning your car for 87 octane (if you go that route). Oh yeah, it'll be slower too.

[frsinpa]

I run 93/94 in my FR-S. Never would think about putting in anything lesser.

Why run the risk of ruining a $26K car all in an effort to save $5-10? Not worth it for me.

[kidgogeta]

I only use chevron 94, (only go to chevron or shell for all my cars). There is no point at all to choose a lower quality fuel, you lose power and mpg. You save money in the end by getting more mpg and cars runs better.

[moniz]

Originally Posted by kidgogeta

I only use chevron 94, (only go to chevron or shell for all my cars). There is no point at all to choose a lower quality fuel, you lose power and mpg. You save money in the end by getting more mpg and cars runs better.

Another person who actually gets it!! Glad to see I'm not alone!

[Lonewolf]

Originally Posted by drifter

OK, SO WHAT IF YOU'RE NOT A CHEAP BASTARD AND YOU WANT TO PUT THE BEST GAS IN, BUT YOU LIVE IN CA AND YOU CAN'T GET MORE THAN 91??? NO ONE HAS YET ANSWERED THE QUESTION OF (or I missed it) WHAT DO YOU ADD TO 91 OCTANE?

Toluene is commonly used to raise the octane level. However, as long as you are putting in 91 from a good top-tier station (NOT Thrifty or USA gasoline) then you should be fine.

[drifter]

Originally Posted by Lonewolf

Toluene is commonly used to raise the octane level. However, as long as you are putting in 91 from a good top-tier station (NOT Thrifty or USA gasoline) then you should be fine.

Thanks. So, you mean like a Chevron or Shell. Also, I live 5 minutes from Laguna Seca race way and I heard they have 100 octane there. I was thinking to add a gallion of that to my tank when I fill up. Still looking into it though

[MrFRsLa]

I guess the question is what did your dealer put in it when your rolled it off the lot?

You should use Premium.

[DeeezNuuuts83]

Originally Posted by Lonewolf

However, as long as you are putting in 91 from a good top-tier station (NOT Thrifty or USA gasoline) then you should be fine.

This. My dad told me decades ago to not get gas at those places. That might be fine for your average, run-of-the-mill cars, or if there are just no other gas stations around, but I will avoid them ten times out of ten.

Going to a cheaper place rather than a Shell or Chevron in the same area usually won't save you much anyway. Where I always go, there is an Arco (soon to be USA Gas) on one corner and a Shell on the other, and their prices for premium are usually within three cents of one another. I don't mind paying a tiny bit extra, especially when you can use cards all you want, while places like Arco usually will charge you a flat 45 cent fee to use a card, which is usually more than what you save unless you are getting a lot of gas or just paying cash.

[Lonewolf]

Originally Posted by drifter

Thanks. So, you mean like a Chevron or Shell. Also, I live 5 minutes from Laguna Seca race way and I heard they have 100 octane there. I was thinking to add a gallion of that to my tank when I fill up. Still looking into it though

Running 100 without being tuned for it is just going to be a waste of your money.

While I do believe the car will run best as intended on 93-94 octane
(hence why all the other states with 93 refer to Cali Premium (91) as "piss water", anything above that without a tune for higher octane will just put a bigger hole in your wallet.

Running 100 octane will most likely result in a less efficient burn, and you will see no benefit without tuning for it.

[Night]

Even if you buy a new vehicle that runs regular I would run premium. Hell my taco is getting the premium gasoline!

[tonystewart]

My recipe..BP Ultimate fill up then add 1 additional gallon of Sunoco GT Plus. Should give a strong 93 + octane rating

[drifter]

Originally Posted by Lonewolf

Running 100 without being tuned for it is just going to be a waste of your money.

Even if you only mix in 1 or 2 gallons of 100 octane with 91? I thought that makes 93 and that's what it's tuned for? fuck this, i'm moving out of California.

[SFTiofoso]

Yeah, California sucks. Gas is expensive, no 93, can't own a gun, etc.

Anyways, if you have a 100 octane gas available to you, and you only add 1 gallon of 100 octane that would only bring your octane to like 91.7. You probably need to add 3 or 4 gallons to get it to 93. A pretty expensive proposition to do it regularly.

With my Si, I knew the dealer would put 87 on that car, and even-though that's not detrimental to an Si like it would be to an 86, I still wanted to make sure the octane was always 91+ in my tank. So what I did, was let whatever the dealer put in there run nearly dry, and then I went to a 76 station that sold 100 octane. Bought nearly a full tank of that, to bring the average octane to 91+. And from then, my car has always been filled with 91 Shell, Chevron, or 76 only. If you live in CA I would recommend you do the same.

If you have any doubts about what the dealer put in your car, just play it safe and assume it was 87.