Regular Unleaded in a LS430? (2023 Update)

The manual says use premium, but that regular can be used without damaging the engine. That's what the manual for my 94 says, anyway.

I'd think you could easily go to the dealer and ask to see a manual. I never buy a car without reading the owner's manual, just to see about things like that.

But more importantly, does the manufacturer specify that 87 octane fuel can be used without causing damage to the engine or voiding the warranty?

My microwave says don't put any metal inside... it is easier to make blanket statements than try to explains the details to the masses.

Not in the owner's manual. The owner's manual clearly specifies "Premium".

I have a better answer than all of you, but it requires a little more work. I put in 1 part 87 octane to 1 part 93 octane...and tilt the mix to get about 91 octane which is what the car requires. I can tell from looking at any point on the gas gauge how many gallons needed to fill up (this took a some time and experimentation). I usually fill at half tank where it needs

11 gallons to fil. I'll put in 6 gallons of 93 octane then the balance of 87 octane. It requires two different credit cards at the pump, too, because most pumps will not work the second time if you use the same credit card...the pump thinks something is wrong. And if you use cash, you have to fill, pay, then fill and pay again (so I don't use cash).

One response here said if you can't afford the fine fuel you can't afford the fine car. My approach is different: It's being value-conscious like this that allows me to afford the fine car!

This has been tested (repeatedly). Performance, on average, drops about the same amount you save (15%). If you can't tell the difference when a car makes 15% less power, then yes, probably makes sense to burn regular. But on has to ask: if you're not caring about performance to this degree, why did you bother paying a lot more for a high performance car in the first place? You can save a lot more than 15% gas money driving an Avalon.

- Mark

Tested by who? Under what circumstances? We're not talking about numbers here, we're talking about real world driving experience. I'm simply saying that under normal (whatever that means) driving conditions, I cannot tell any difference between the regular and premium fuel. As I stated in my original e-mail, if you hook up a dynamometer to the car, you probably will easily measure and can report the difference. So what?

BTW -- I don't only buy LS430's for their performance. Yes, it's a factor, but there are a LOT more features to the car than just "GO". If I wanted a "GO" car, I'd buy a Ferrari (which has NO other features other than "GO").

...and the beat goes on ...

Hi New owner, you are dead wrong.

Last year when one of the AZ pipeline from Texas bursted, we have shortage of mid-grade and premium unlead. We could only buy regular gas from CA for almost 2 weeks.

Anyway, there are 3 large fuel tanks at the distribution center. Each one contains different grade of fuel stock. Each gasoline brand will mix their own secret detergent package, but the base stocks (comodity) are all the same.

For the other question, the reason I use Premium is not for gas mileage. There is no different in gas mileage. The car just run rough, make more moise upon accelerate with regular gas when the weather get hot. Even at freeway speed, it can feel it is noisier and rougher.

When i switches to premium... Sweet.

Don't forget that at 110F, the AC generates quite a lot of drag. Also, the air inlet over the asphalt in traffic must be over 120F. The air density is thinner. The exhaust is hotter because the inlet temperature is higher. Go ask the airliner pilot. When the temperature is hotter, the plane needs longer runway for take off.

Car companies are not stupid to specify Premium fuel if it does not need it. It's a disadvantage.

That's just plain wrong. How the heck would they know what kind of fuel you put in the car? You really think they're going to extract some fuel from the tank and test it to determine? Yeah, they've got nothing better to do than that.

You are kidding, right?

Let's say premium gas is $0.25 higher than regular. You are saving $0.125/gallon. On a 20-gallon tank, you are saving $2.50. How long do you have to do this before you can afford a more expensive car.

You have to be an engineer -- probably software, right?

Hey, do you also mix half diet and half regular soda because your engine can handle 55 calories but not 110?

My father-in-law used to check the ads in the paper every Saturday morning and then drive clear across town to save 5 cents on a can of beans. We used to kid him about the 10 cents of gas he spent to save the 1, but he was raised in the depression and couldn't do it any other way.

It's a free country.

-- Owner of a 1999 LS400, purchased certified in 2002 and a 2001 RX 300, purchased certified in 2003 For email, use Usenet-20031220 at spamex.com

Like I said Carl, if you can't tell the difference between a 300-hp car and a 265-hp car, go for the regular.

- Mark

About what? There being only one "grade" of gasoline. Nope. There is only 1 grade of gasoline coming out of the refineries, 87 octane regular unleaded. Any/everything else is a blend. Also the gasoline flowing through the big interstate pipelines is 87 octane regular, nothing else. Trust me, I know what I'm talking about. I work for one of the major interstate pipeline companies in Houston, TX.

Mid-grade is most commonly a 50:50 blend of premium and regular. Secondly, the best selling gasoline is regular unleaded, therefore if a pipeline ruptured somewhere there would be a general shortage and so likely the preference would be to sell what there was of it in the market with the highest demand, as regular.

And very likely 1 is Regular and 1 is Premium. Most likely the 3rd is diesel. Mid grade is most commonly a 50:50 blend of regular and premium. There is no reason to put mid-grade gasoline in storage.

All the same meaning 87-octane regular unleaded.

I am dead serious.

So how much have you saved so far?

-- Owner of a 1999 LS400, purchased certified in 2002 and a 2001 RX 300, purchased certified in 2003 For email, use Usenet-20031220 at spamex.com

D.D, where can you buy 93 octane gas?

Long time ago Exxon and Unocal used to have 93 octane (leaded I believe). Not any more.

Don't know where you guys are, but every gas station in Texas has 93 octane Premium. And 91 octane Mid-Grade is what the professor is trying to formulate. Most have the mid grade, also.

BTW, my wife's RX300 runs fine on 87 octane regular.

D.D., you are just trying *too* hard!

In the Western states, the octane grades are 87,89, and 91. No 93 everywhere. In Utah, the regular unlead is 2 point lower I believe, but the premium is 91.