arcteryx

I just got back from a 2600 road trip. Along the way, I was able to use some real gas, meaning no ethanol. This got my wondering- is regular pure gas at 87 octane better than e10 with a 91+ octane? The difference between the two was 90 cents (2.02 vs 2.92) which is about $20.

FYI, I used the premium and did notice a 1-1.5mpg increase over ethanol. You can find stations at www.pure-gas.org

montezstop

The Oxygen sensors are effected by the use of lesser octane gas.

rjm

And the source of your information is..............???

warminwisc

This thread or any other on LS gas I question also. Have you seen a flurry of o2 sensors, cat problems or anything else supposedly related to fuel in links on the forum?. Not me in 5 years. It is ok to ramble with little support from studies and everyone has an opinion on. Run manufacturer gas or whatever it seems.

Lavrishevo

iTrader: (1)

It does say in the manual to not let the car idle for more the 20 min as this can damage the cats. Both on my old 99 and on my 04. I do remember when I had to replace the cats on my LS400 that a tech told me low octane fuel can have an affect on the cats. I don't have any proof of this but my 99 cats failed at only about 75k miles. From what I understand the previous owner ran only 87. I have no proof but it's not common for cats to fail unless something is taking a toll on them.

warminwisc

I was given the same advice on low grade fuel effecting the cats by my Lexus Tech. He was not real definitive about it, cars are cars to these guys.

rkw77080

The LS430 is equipped with what is called the Three-Way Catalytic (TWC) converter. According to the attached literature, low octane fuel does not seem to be one of the primary contributors to TWC failures.

Lavrishevo

iTrader: (1)

I agree and disagree that octane does not affect the converters. Here is why. In and of itself the octane rating has nothing to do with the cats. It is all about the engine. If running poor quality and / or low octane fuel causes the engine to have misfires or not burn all the fuel it will send unburnt fuel down the exhaust system and this will coat the interior of the cats with soot and eventually ruin the cats. Enough of it can actually set the cats on fire. We have all been behind a car running rich and you can smell the unburnt fuel. This would also affect the oxygen sensors. Knock sensors are designed retard the timing to help prevent this but how well they work is anyone's guess. The more efficient an engine equals more fuel being burned in the engine and not pushed out through the exhaust system. This obviously means more power and gas mileage. In a high compression V8, higher octane = more effeciency. This is why the LS states premium only.

AlexusAnja

The gas companies have us by the ***** no matter what. When gas was $3+ for regular, regular and premium was usually about 30 cent difference, now they are most places almost 50 cent difference. Did those additives go up that much?

Lavrishevo

iTrader: (1)

It's not about the additives. Its about the octane level. High compression engines need higher octane to run efficiently. Higher octane levels prevent pre-detonation. This is also of most turbocharged engines.

brybo86

Most pumps have a single hose for all 3 grades, you just select what you want midgrade is simply a 50/50 mix of 87 and 93

So i'm not sure how it can be "stale"

XJSFan

I have always used 93 octane in my car and would only consider 87 octane if I was on a long road trip via the freeway.

Boomer01

It's around $0.50 more for premium over regular unleaded here also. Another racket is the steadily increasing cost difference between E10 and no ethanol gas. It used to be around $0.10-0.20 and lately I've seen it as much as $0.75 more per gallon for pure gas.

campisi

this is quoted from my post on this thread (page 5) in '05. Wow, time has flown ... 10 years later I'm still filling it with 87. Runs like new. 91 octane is +20 cents over 87 octane where I live..

tradosauru

I'm on my 2nd tank of gas since I bought my LS430 a month ago.

The first tank I used 87 Octane (No ethanol). -$2.20/ gal

The 2nd tank I used 89 octane (10% ethanol) - $2.07 / gal

The next level is 93 octane (10% ethanol) which is $2.38/gal. This is $.60 higher than regular ($1.78 / gal)