Octane relates to detonation relative to higher compression engines. The higher the octane, the less detonation when it’s compressed, or stated another way, lower octane gas ignites easier. I believe the 400’s have a compression of 10:1, not really that high in the world of high compression (race prepared) cars. For the past 9K+ miles, I’ve been running 87 octane and have yet to hear a knock or ping. Just my $.02.

And you haven’t seen the cap to gas prices especially in the west with broken distribution lines. Hey, someone has to pay for the political campaigns….

Our cars have knock sensors, so most likely you will never hear the pinging. A slight (unoticable) loss of power will result. Hit the dyno and see for your self. I've seen differences of 7-9 hp due to gas variation.

93 only!

Florida. Besides the lower the octane the faster the fuel burns = less MPG..
Not to mention higher amounts of carbon deposits on your valves.


93 87

I have always gotten more distance out of higher grade fuel in v/s "per tank" comparisons, you do get your money's worth.

93 @ Exxon-Mobile....94 @ Sunocos i would never use lower than 91 on anything even it eats regular gas....just pay the extra 9 cents a gallon it helps in the long run

What about using Shell's regular grade, Their new advertising campaign claims that their gasoline yields more mileage per tank than the other competitors.

VP C16 is 117 octane. That's what I run in my Turbo TA, but then again, I'm running 24psi & a T-70.

As for the Lex, it gets only 93. On average I get 400-450 miles on a full fill-up with a mix of city/highway driving. Car has about 135k miles also.

WHY ON EARTH, would you want to put lower octane gas in a Lexus SC400 anyways?

If you want to save a few bucks at the gas station, go buy a Geo Metro and put 87 octane in it.

You bought a Lexus SC400 a beautiful FAST Luxury coupe.

ACT LIKE IT!!!

SC400866, That’s one of those comments that make absolutely no sense, unless that is, you’re extremely status conscious, and if that’s the case, just put a sign on your SC400 that says, I only use high test. It doesn’t have to do with the dollars, just what works well for the individual. If Lexus told you to run only 110 octane or better, would you? As to your capitalization, are you trying to reflect shouts and authority?

To rephrase your quote:
It makes no difference what grade you use, it's basically a matter of personal perference.
Studies show that there is no noticable difference.
http://www.usatoday.com/money/autos...remiumgas_x.htm
It all boils down to how much you are willing to pay and give to the oil companies profit margin.

Exactly how is a Lexus owner suppose to act?
Am I to act any different if I also drive an American nameplate vehicle?. Get real!

EmeraldLexuSC3, VERY WELL STATED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! See, I can use capitalization too.
and even bold it......

So I wonder what year SC and the mileage on this high octane eater, and again, tell me how I'm supposed to act???????.

Then again, maybe a tune up would help.....

Folks, it DOES matter what you use, as it needs to be what the manufacture states. If it says use premium- use premium. If it doesn't say, then use regular unleaded. It disclaims that for a reason. The ECU is adjusted for that octane, and expects that octane to be run. Using something different will lead to poor meilage/performance.......the butt dyno might not notice the changes, but a real dyno will. I have seen a difference w/ my own eyes at the dyno before.

Using higher than necessary octane is a waste of money, raises temps 1-2 degrees, and lowers fuel economy. Using lower than necessary octane will have performance loss, and quite poor meilage.

We've run a car w/ 87octane (low fuel light on), made 2 runs on the dyno- then added 5 gallons of 93 octane made two runs, then pumped the fuel and ran 2.5 gallons 104 octane. The best performance was the 93 octane. Guess what the owners manual reccomended in the tank? Guess what gave the best power. There is no need to put higher octane than recomended, but putting lower will not give peak performance. Anything other than what that lil' sticker says is a waste. I've used lower test gas in my 400 before and didn't notice any difference power wise (butt dyno) but did notice that I barely got 300 miles to the tank, when I normally get in the high 300's. So when you factor in the meilage loss to the extra cost of the premium gas, its actually cheaper in the long run to pay more and drive further than to pay cheaper and fill up more often. Lexus says use premium- I've actually tested different octane gas', and now know first hand with stone cold evidence that using what the owner manual says is what works best.

Luckily we live in a free country - so you can do what ever you want, but lets not mis-inform people w/ opinions rather than facts. So thats why I felt compelled to share my experiences.

Isn't it great to be alive in America were we can disagree on simple perspectives such as octane and MPG's. I don't advocate any particular thing for anyone other than myself. You get 300 miles per tank on 87, I still get 22 MPG mixed city and road (400 per tank between fillups of 18 gallons) on 87, same as i did with 93, and granted, I don't have a lead foot. True, 93 gives more HP and I wouldn't argue that point. Honestly, this topic has been beat to death, and discussed in the past on other threads on CL. To each his own..... Thanks to all for contributing their opinions.

HAHA,

Maybe I shouldn't have started this thread!!! Too many arguments!! Do we need a group hug!!

Peace

Jonny
Dx3

What I wrote sounded rude and obnoxious. I didnt mean to sound like that.
All i'm saying is regardless of the performance indifference between 87 or 91, why would you want to go for the cheaper one?
Right now in sac/roseville CA area the price difference is about .20-.25 a gallon. 16 gallons equals $4.00 a fill up. You spend that on fast food. Its not enough of a savings to risk it for me.

But, to each his own.