glock22x

If the ES350 engine gets 272hp from 91 octane, will filling up with 94 octane increase performance or is it at max efficiency already? It might be a stupid question, but I have no knowledge of mechanics

ES350Bob

I used 93 octane in my former, dealer put this tank in for my newer and I am sure it is also 93 octane as we seem to have 93 then next down is 89 here.

Several posted on octane before and said they are using 89 octane with no difference in performance they noticed though in extremely cold climates I'd be sure and use at least the 91 octane suggested during the winter months.

You might get a very slight bump in HP with 94.

BillP

It's not a dumb question and maybe somebody that knows for sure can reply, but I doubt Lexus/Toyota developed the programing to optimize ignition timing, air/fuel ratio, valve timing, ect to take advantage of 94 octane, so I think it will be a waste of money to put 94 in the tank. Even if the ECM could optimize for 94, the power gain would probably be just a couple hp. Like a lot of other people here, I using 89 with no noticible seat of the pants difference.

garsarno

I wish the 94 octane would relieve the cold morning "cannery works" noise!

nyardich

I would give anything to stop cold start "cannery,Diesel" noise.
It drives me nuts......................................
Nick,
Aliquippa, Pa

ES350Bob

Nick,

Get another opinion on it, note when you open your Lexus driver door and read sticker it says Toyota Motors on it, your only other opinion on your car was from another Toyota source.

Or, just try turning stuff higher volume to drown it out if you want to accept the explanation given you by your friend who works for a Toyota dealer.

I can tell you this, to a person, no second opinion was offered me unless they had the car in front of them where they could hear it themselves, both refused to even try to guess over the phone for me.

Lexmex

Maybe Pheonix can pipe in on this, he is an absolute master on our Lexus engines.

I can tell you that with my RX300 for instance, I have used racing gasoline and no difference. There is something related to timing, but I have no idea how these ES350s are rigged up.

Kaius88

The gas station near my house has the most expensive "regular 87" around and the cheapest "supreme 91" around. The difference in price is $0.07 per gallon. I'm glad i use the supreme. I am encouraging my wife to use the supreme on her Toyota Highlander as well... I mean what the heck...

ESsearch

The octane rating of gasoline is not indicative of the power available from that gas. In fact, the higher the octane rating, the slower the gas burns. The only reason to switch to a higher octane rating is if the engine is pinging and in fact, the highest hp output for any given engine comes from the lowest octane gas that does not cause pinging at it's peak tuning settings.
Older cars gave us an audible tuning clue (pinging) when we switched to a grade too low. Modern engines have electronics to prevent the potentially damaging pinging so you will never hear it. Basically the electronics will retard the spark timing from the optimum setting until the pinging ceases, resulting in a loss of a few hp. The loss is negligible for most street cars and that is why many in this forum say they use 89 octane with no apparent side effect. I would guess it only causes a loss of 5 or 10 peak hp at most and I doubt many of us are redlining our cars regularly.
A manufacturer recommends the optimum gasoline rating required based on the tuning needs of the engine (91 for the ES350). If you want to use a less expensive gas (89) it is your choice and I highly doubt it would be detrimental. Using anything higher (94) will also not cause any problems but could cause a tiny loss in hp (guessing 1 to 5) from the slower burn and usually will be costlier and therefore a waste of money.

Pete

amf1932

This is taken right out of the ES350's Owners Manual

LexBob2

The 3.5 engine is rated at 268 hp on regular unleaded in the Camry and Avalon. In the ES it's 272 hp on 91 octane. I read that 91 octane is required to get "the manufacturers advertised horsepower", but 87 octane or higher won't harm anything. Possibly just a slight loss in performance.

Pheonix

The higher the octane, the less power in the fuel & the worse the emessions. If you do not tune for higher octane fuel, you're throwing away money & getting less power. Pinging is bad. The lowest octane you can run without pinging (triggering knock retard) is the "correct" octane to use.
The engines are programmed to run 91 octane. Barring a problem like hot spark plugs, carbon in the combustion chamber, etc. Higher octane than that will simply raise emessions & lower power.

I wouldn't run 87 *all* it's life, but it's not going to hurt anything afew tanks here & there.


If you're worried, install water/eythyl injection & run 87 all you want for it's entire life. Wind up with 110+ octane, and spotless combustion chambers. hahahahahahahaha

cowdung

This guy knows what he is talking about. Use the lowest grade gasoline and dump some regane or redline complete fuel injector cleaner every 5000 miles and you'll be good to go.

Macklin

Well, then what is the better choice....89 or 93? The two or three stations I frequent all carry 93, which is what I have been using.

ES350Bob

Mack,

See Alan's post from manual..87 octane is fine for the car and will not hurt it or they sure wouldn't print you can use it as long as the fuel meets the standards listed at bottom of info page Alan posted. I haven't done it yet but will try it in the next few weeks.