Losiracer2

I put on close to 30k hwy miles on my 97' from 251k to 280k in about a year's time using Costco's reg unleaded (87 octane) and didn't notice any degraded performance of the engine. I was driving 80 miles a day all highway and the extra $0.60 a gallon cost me quite a bit every week if I were to use premium, about $10 a week or $40 a month which adds up quickly.

Since nobody has any physical data to prove otherwise, I would say its fine to use if you drive highway miles and not a lot of stop and go driving, just constant, light throttle long stretches. I still was able to get about 27mpg hwy when using the stock 16" wheels, but it dropped to 23mpg when I had my 20" wheels with 245/35R20 tires.

I now use premium, but I have 93 oct. here in MI available and drive purely city now in my 99' LS. I don't drive nearly the amount of miles I was doing at my last job so the cost isn't as important anymore (14 mile roundtrip to work). I might consider going the Shell route as someone had suggested above to see if it makes any difference over Costco gas.

fondu

I have not put anything other than 90 octane ethanol free since i bought it a few months ago. Im no engineer but i assume that 1 octane rating lower isn't going to cause knocking or pinging. Then again i could be totally wrong.

27mpg on the highway? Was that going 70mph? Or 60-65? I havent done any long highway trips yet. Ive been getting a solid 20mpg going back and forth to work which is 18 miles each way. The route has some stop and go but a good 14-15 miles of non-stop at 35-40mph.

I would be extremely happy if i could get 25mpg on the highway at 70mph.

jaaa

I got an average of 27MPG on an 1800 mile trip to New Jersey from Colorado recently on my 1996 ls400 with 258k miles. I think it would be an average of 70 to 75 miles per hour on the western half of the trip and 60 65 on the eastern side. I only got 25 MPG on the return trip, but hit head winds on that leg and it is uphill quite a bit of the way. I only get 18/19 in city driving.

LS400FAN

OK here's my reasons for doing what I do with gasoline. First of all I am no engineer so what I'm saying may not be totally accurate, but here's what I do know. Gasoline engines tend to provide a more "complete" combustion in your cylinders with higher octane fuels. Better combustion "generally" leads to better performance (power and mileage) imo. Now, this was always true with older model year cars, however with the highly advanced engineered engines over the past 20 yrs.or so will probably provide the same or even better "combustion", coupled with iridium spark plugs, high energy ignition systems and an assortment of sensors/electronics, with lower octane fuels. Even with today's advanced engineering technology, I still believe that higher octane and "nitrogen" is an unbeatable combination, especially if you can eliminate the corn(ethanol) from your engine. None of this is very practical however, if you trade up your cars every few years or so, carbon buildup and the junk that ethanol leaves behind will most likely not be an issue, but if you are in love and "married" to your machine like I am and plan to keep it forever, then giving it the best possible tlc becomes paramount in maintaining it. Case in point, if someone offered to trade me straight up by "giving" me a late model LS460 low miles for my '95 LS400, I know many of you won't believe this, but I would decline the offer. So this is just me, it is what it is, what can I say

bradland

I don't want to go down a fuel rabbit hole so to keep it short and sweet a lot of info will be glanced over...
The reason the manual recommends a certain octane rating is rooted in the compression ratio of the engine. The 1UZ was designed with a 10:1 compression ratio which is considerably higher than most cars. Most engines are designed somewhere between 8:1 and 9:1. It's not new technology but cars with higher compression engines have become more common in the last few decades. Higher octane fuel is not necessarily "better" or "cleaner" than 87. Higher octane fuel will burn more completely, which is essential in higher compression engines, and is often confused with burning cleaner. There is a bit of marketing hype behind all this, higher number (92 vs 87) higher price etc. In a nutshell higher octane fuel is not better it's simply APPROPRIATE for the 1UZ. If your car is designed to use 87 there is little, if any, benefit in using 89 or 92. It doesn't matter how new old expensive etc your vehicle is, if it's not designed to use higher octane fuel it's not necessary

LS400FAN

Well said, you get no argument from me, thanks for putting this to bed. That said, I will never get it out of my skull, high octane and nitrogen for my machine, and zero ethanol whenever possible.

430SLOwner

Please ... go back down into your hole.... Higher octane is BETTER in those engines tuned to run on higher octane. When Toyota says the engine requires premium, believe it. Computers may adjust the ignition system to accommodate lower-octane gasoline, but, the knock sensors and ability to retard the spark timing doesn't mean premium is unnecessary. Run a tank with 87 in an engine REQUIRING 91 or higher and note your mpg. Then run a tank with 91 under identical driving conditions and note you mpg. Your horsepower and mpg are both higher with 91 in engines tuned to run on 91 or higher. However in engines designed to run on 87, run the 87 and save your money because you won't see the same benefit in those.

bradland

Interesting how you chose to edit your post and remove the original video (linked below) which is obviously not credible and clearly where the verbiage contained in the post is COPIED from.
If your knowledge is based entirely on YouTube videos you might want to screen them more rigorously and spend more than 3 minutes compiling knowledge before you post. Also editing previous posts in order to delete what you have already posted (aka CYA) does no one any good not even yourself. Congratulations on your YouTube education it displays an admirable level of dedication. You MAY enjoy the advanced content found on the Scotty Kilmer channel



Original video replaced during edit-

430SLOwner

Thank you again for your kind words.... Your uplifting posts of encouragement and advice are always appreciated. But, am surprised that you recommend Scotty Kilmer so highly. It is widely known that he makes well over $1.5 million a year on YouTube with his home garage mechanic advice. But, I would not have expected you to be such a big fan of him....

YODAONE

Who is this joker??

Lower octane requires less spark energy?

We do know that in old school engines, higher compression engines typically require higher octane fuels than lower compression engines to stave off pre-ignition and, or, detonation.

Higher cylinder pressure in a higher compression engine may increase resistance to sparking, but that really isn't an issue in contemporary ignition systems..but resistance to the spark jumping across the gap or igniting the mixture is not octane dependent.

Higher octane allows more advance of timing over lower octane fuel.

With 1UZ-FE , the knock sensors communicate to the ECU to optimize ignition advance.

If using lower octane fuel, the ignition timing is not optimally advanced, and the fuel mixture is enriched to avoid engine damage from pre-ignition or knocking.

Those who routinely use lower octane fuel in the 1UZ-FE experience increased carbon build-up in combustion chambers, intake manifold and throttle body..

Using lower octane fuel in the 1UZ-FE reduces engine power and increases fuel consumption.

Engines designed for 87 octane (lower compression) may not benefit from 91or 93 octane fuel...unless the ECU can take advantage by advancing engine timing or leaning fuel mixture.

Contemporary direct injection gasoline engines can go with even higher compression ratings without higher octane fuels...so how does octane of fuel then effect spark efficiency?

Kindly remove the link to that guy's YouTube link from this site.

Thanks.

LS400FAN

Well this all goes back to my point of using Shell premium with nitrogen. It stands to reason that if your 1UZ-FE "requires" premium gas why not go with the one that dissolves the performance robbing carbon the best? I kid you not, the stuff works!