mkendrick

So I found a PDF spec sheet for the LS430 on Lexus's Canada website. Weirdly for fuel requirement it says: "Premium fuel recommended."

What are your guys' thoughts on that this may prove that our LS 430s will be just fine on 87 octane? I'm still a bit hesitant to use 87 all the time.

WILLYumD

Straight from the Owner's Manual (US):
The ECU will account for knock and pull timing on 87.
But... the issue is that the ECU is expecting 91.

That means it is constantly going through a loop of:So, it'll be "fine" the car will continue to run. Just don't expect your engine's health to be optimal in the long run.

EDIT: I mean... if you were wild, you could get the car tuned for 87 LOL

AVSRacing

It's the same thing as you can eat McDonald's 3 meals a day.......

Bocatrip

Ours cars are made for High Octane. Running anything else will result in a loss of power, poor gas mileage, and eventually a good chance to damage the engine. Why risk it?

Lzam

It's not worth it in the long run.

alextv

This high compression engine is optimized for 91 octane but the computer will adjust the timing for using a lower grade and it just won't be optimized at it's highest capability. You will loose a little bit of power and about 1 mpg of gas using the lower grade. There is no knocking or pinging that over time could damage the engine as the computer does a fine job adjusting. I know quite a few people that over15 years ago at one of the gas price spikes switched to regular and never went back with no problems at all except a little loss of power and 1 mpg decrease. As far as I can see there is no verified documented evidence out there that shows it damages the engine. I might be wrong but if someone here knows where it is please show me and others where it is.

demark1

It is a risk/reward thing. I get around 18mpg on a 65/35 local/highway split. I drive around 5-6k miles/year, so 300 gallons or so (ouch). Regular is no around 70-80 cents / gallon cheaper (87 vs 93) here. I blend my own 90/91 out of a 2:1 9 vs :87 ratio roughly. Around $140/year more at most for the 91 blend. I think I notice some mpg difference on pure 87 when I have done that on occasion, and cannot tell a perf difference. I am careful where I try to save money, however. I had to replace 1 cat 3 4 years ago, etc. so do not want to mess with the engine. I also change my brake fluid every 3 years or so and my oil every 7-8 months (6 months ideally but I get lazy or forget) and save by using conventional oil when the quick-lube place charges too much more for synthetic. So I am ok with conventional oil, but not routinely with 87 gas. There is no absolute answer here since we are not engineers. It is probably 100% fine to use 87 octane, but perhaps not definitely 100% fine. And synthetic might be worth it, but if I change my oil regularly (and not myself) I'd rather same some cash unless there is a special on the synthetic. I feel uncomfortable with the long-term use of 87. My parents have a 2009 ES350 which also "needs" 91 and it has been flawless since new on years of 87 gas and 130k+ miles. It's preference and comfort level. I save some money by having dropped comp/collision on my LS. No absolute answer... this is my comfort zone.

JaySco

Why is that weird? It’s not a random number that a manufacturer throws out there. They have specific engineers that design the engine and programming to run optimally with a certain type of fuel. Will it run on a lower octane? Yes, that’s why it says recommended and not required, it’s not a nitro-meth injected race car. Will it be fine with always using 87? Possibly, possibly not, I’m not an engineer.
My thoughts? The price is negligible, I’ll continue to put 91.

This question always got to me on the Miata forums back when 87-91 octane was .20. This always came up, and we’re talking about $2 a tank difference. $2!

CA2WALS430

Echoing others, its not worth it. I have heard one thing before that what you save in individual fill-ups you'll pay for in more fill-ups, meaning reduced economy. I had 1985 Nissan Maxima that did not require premium, and I fixed some knocking and pinging by using premium, way cheaper than the shop bill. Considering it was the Z engine, Nissan should have required it, but I was 13 in 1985 so I have no recall if 91 existed.

JffGRY706

there are 2 myths about using regular
1 you will clog your fuel rails and injectors and spend more on that
2 you will clog up the catalytic converters and spend more on that
your car do what you want but I like mine and use premium whenever possible and if the previous owner used regular than you might need to use premium a long time to get it back right

BigBoomer

The Owners manual states to use 91AKI (RON+MON/2) or 96RON fuel. Here in the UK our "Regular" is 95RON so I just use that as it's close enough.
The extra cost to get "Super" (97-99RON) just isn't worth it. My typical fill-up is 75 litres and the price difference per litre is 0.15UKP, so that adds up to over 11UKP more per tank or US$15 per tank.
However, at 87AKI you are WAY below what is recommended and that will affect the engine performance and potentially it's reliability.

mkendrick

Thanks guys for letting me know your two cents. I guess l was hoping that perhaps this was proof that the 3uz-fe didn't need premium (91+ octane) similar to how manufacturers will sometimes put out different engine oil requirements for different countries for the exact same car model. Nonetheless, I'll probably just go back to getting premium most of the time or maybe do a blend with mostly premium. 👍🏼

BigBoomer

Different engine oil requirements in different countries normally relates to the climate in those countries. You will need different oil if you live in Canada 🥶 compared to if you live in Burkina Faso 🥵.
You can run lower octane fuel when at altitude, but it is still not recommended as it will affect performance.

chasdl

Hi Folks, I'm late joining this thread late but have something to add. For context, I have an '04 LS 430 and love it. It still, even today, runs fine.

Recently I discovered a gas station in my area that sells ethanol free fuel. Unfortunately, it is 90 octane instead of 93, but I decided to try it anyway.

The result has been extremely positive. After running a couple of tanks through to get the ethanol loaded gas out, I'm seeing an increase in gas mileage of around 6% and a slight, but definitely noticeable, increase in power. I'm quite pleased with the result.

I just wanted to share that result in case anyone else was thinking of using ethanol free fuel. If I'm not mistaken, the law requiring the addition of ethanol was passed in 2005, so my car was definitely designed to run without it. If the 90 octane is not a problem (i.e., does not produce any knocking), I intend to keep using this fuel as long as I can.

My reading of the other posts on this thread is that 90 octane, while sub-optimal, should not be a major problem. If anyone has a different opinion, please let me know. In any case, getting the ethanol out has been a significant boon, and I highly recommend using it if possible.

Best to all..

jimisbell

I drive a LS430 and an SC430 I have been running both the SC and LS on mid grade (91 octane) for 10 years with no knocking and no degradation of mileage. Available at the pump are 87, 91, and 93 octane, all adulterated with alcohol.
However I did some extensive studies on the ethanol mix a few years ago. Here it is 10% ethanol and getting the fuel without ethanol is possible at any station near the water because ethanol will deteriorate the plastic in boat motors. Its legal to put in the car but it costs 10% more because adding the ethanol costs 10% more!!! surprise surprise......
My studies were on the mileage increase you get because of getting the ethanol out. I found that mileage increased 10% Wow, surprise surprise, when you get a full gallon of gasoline instead of 9/10ths of a gallon, you get 10% more mileage. The ethanol is just an inert additive!!! I ran these studies on a Honda Insight. for over 5 years in a checker board fashion. It was always the same, no alcohol yielded 10% better mileage. In other words a tank of real gasoline would get me 10% further down the road than 9/10 s of a tank of gasoline adulterated with 10% alcohol. And it would cost me 10% more. And do this all on the backs of the American consumer of gasoline!!! It was as though the government had legalized the adulteration of sugar with 10% sand. Your coffee would be 10% less sweet but a little more gritty
Recently the spread on price has gotten greater so its not worth looking for the alcohol free gasoline anymore.
What it amounts to is a government attempt to reduce gasoline use (which it didnt because miles per gallon of REAL gas remained the same) and to subsidize the US corn farmers, at the expense of higher food costs in Mexico where corn is a major ingredient. And you and I are paying for it.
Its a case of your government making a mess of things by trying methods with unintended consequences and not being able to back down because they are always right.