LX570 - Premium (93) or Ethanol Free (89) ? Which is “Better”?

[SnoViking]

Question for the community;

I have a 2008 LX570. My local fuel station just started offering ethanol free 89 octane. The sticker on the tank (and in the owners manual) calls for premium fuel which I have been running. I’ve read a bit online and know that the LC200 (and Tundra), which uses the same 5.7L motor, just calls for regular fuel. Is there a specific premium fuel tune for the LX or is that just how Toyota is squeaking out the few more horsepower?

Would running the ethanol free 89 be ok?

 

[Tex68w]

From what I understand, and I could be wrong here, the LX is tuned to run on 93 octane and that's how it gets its few extra horses over the 200, but it can run on regular (87) without issue and without causing harm/damage to the motor. Someone please correct me if I am wrong.

 

[bloc]

The extra 2hp are well within margin of error considering it is about .5%. While it is possible, there is no solid evidence that there is a different tune. We do know the compression ratio is the same. It being higher would be one instance that clearly makes the case for higher octane. It is possible for ignition timing to be different but again.. where’s the horsepower? For the record the 3UR does have knock sensors to adjust timing in the event of a knock condition. Not that this is a long term good plan for running less than the “actual” needed octane rating.

Lots of guys run 87 or 89 in their LX without issue for hundreds of thousands of miles.

“Requiring” premium is standard for the lexus brand, however.


Is premium better? Maybe. Considering what I wrote above about CR and HP between the two platforms, and the clear benefits of a gasoline engine actually burning gasoline, ethanol free would benefit LX570 owners more, IMHO.

 

[Chrisleduc1]

 

[tbisaacs]

Oh boy.

 

[mcgaskins]

Oh boy.

Agreed. Kinda ridiculous how often the same questions are getting asked around here.

 

[SnoViking]

Agreed. Kinda ridiculous how often the same questions are getting asked around here.

Maybe I phrased the question wrong. I did search (and even read) for previous threads (like the one from May of 2018). My question was less about octane (87 vs 93) and more about 93 with ethanol vs 89 without ethanol.....

 

[Tex68w]

I don't think I'd care either way honestly and I bet I end up putting regular 87 in ours more times than not.

 

[TeCKis300]

That's a really interesting option you have there with the 89 octane ethanol free gas. I'm curious about the pricing of this gas relative to the regular ethanol 91 octane, as this pertains to the possible trade you're choosing between.

Recognize that ethanol vs no-ethanol, and 89 octane vs 91 octane are really two completely separate things. Yet they are being brought together here as that is the choice you have between.

The non-ethanol fuel will have more energy content enabling better mpg efficiency, versus any fuel that is spiked with ethanol. That is because ethanol has less energy content by volume. Your opportunity is better fuel range per tank of fuel. Not sure its relative cost compared to the 91 ethanol, but at least you should be getting incrementally more range per tank.

The 91 octane ethanol fuel (regardless of formulation) is the documented spec'd fuel of choice for your Lexus. As that is the "required" fuel that the engine calibration is tuned to. Others will tell you differently that it is a "marketing" thing. IMO as an engineer, as one that has actually tuned Lexus and Porche cars in the aftermarket, and as one that has read tons of engine and knock logs from various setup and octanes of fuels, engine calibration for fuel octane is absolutely a real thing.

Generally, dropping from 91 to 89 octane will slightly reduce power and engine efficiency. 89 without ethanol could easily make up and more than compensate for the efficiency loss. Yet still cost an tiny reduction of power.

Given Toyota's conservative nature and 89 being much closer to 91, in this case, it might be an opportunity for you to increase gas tank range. Is there any cost benefit?, not sure until you fill that piece in.

If there were no cost benefit, my personal choice would be to stay with 91 octane as recommended by Lexus.

 

[Whiskerz]

My experience with my Honda was about a 3-4 mpg improvement on non-ethanol vs ethanol gasoline. My f-150 showed less but still over an mpg improved. I would not be shocked if you saw a mileage improvement with non-ethanol.

 

[SnoViking]

I stopped and topped off this morning. I had about 3/4s of fuel left and figured I'd "walk" the LX onto the ethanol free fuel and let the ECU adjust. The 89 EF was $2.869/g and 93 was $3.119 which is about 9% cheaper. Im not too focused with the cost savings as the potential benefits of no ethanol would be nice. But in the end it may be a win-win.

 

[32cls6speedmt]

our ethanol free gasoline is 87 octane but same price as the premium ethanol gas.

 

[lxid]

We have 91 ethanol free gas here and I have tried it for a few tanks. I didn't notice any impact on MPG or performance. I couldn't stomach the price on it after a few tanks and no gains. There are so many variables that can impact MPG it's tough to do a tank by tank comparison without driving the same. I continue to use the non-ethanol in all my small engines seems to make a big difference in how they run and the carbs don't gum up.

 

[32cls6speedmt]

I agree with you about the small engines with ethanol free gasoline.

 

[ArnieC]

Ethanol free is great for antiques and small engines.