You lucky dog!

 

Not so lucky because she takes it all back in carbon taxes.

 

Can't have it all!

 

yes but the point is, you don't need that extra performance unless you're racing your car or you're driving at 100mph or something.. its like a lamborghini, yes they go superfast but when will you really use that speed unless you're breaking laws?
its pointless unless you're going to a race car rally. and on top of that, lexus isn't even a car where people buy it for speed and quickness, it's for the looks and comfort

anyways, i understand what you guys are saying. yes the documentary is saying premium oil is a scam for regular cars, i fully get that.

but when you dig deeper you find out lots of luxury cars where manufacturer says premium is required, can run just fine on regular. so to me premium is still a fraud unless you're driving a rolls royce or bentley.
if you guys are dead set on using premium go for it bud.

 

Then you're saying you feel you know more than the people that engineered this Lexus. I don't have that same confidence in you, sorry lol.

I want my car I paid $80,000 for to operate the way the people who designed it designed it to. They say I need to run premium for it to do that, that's what I'm going to do. I don't want it to run "fine", I want it to run the way it's designed to run.

Lots of things about this car I don't "need". If I was going to buy something that only had what I "need" it would be a midsized 4cyl car.

 

Time to debunk another myth.

Lets look at what Porsche has to say regarding their luxury car the Panamera.

The engine is designed to provide optimum
performance and fuel consumption if unleaded
premium fuel with 98 RON/88 MON is used.
If unleaded fuels with octane ratings of less than
98 RON/88 MON are used, the engine’s knock
control automatically adapts the ignition timing.
Porsche recommends that you use fuel with
at least 95 RON/85 MON in your vehicle.

If the recommended fuel is not available, you
can also use unleaded regular fuel (91 RON/
82.5 MON) in an emergency.

Lets just ignore the manual because they are over reacting.

 

One case in which was proven to me that higher octane does not produce more power, was when I tried going back and fourth between 87 and 93 on my motorcycle, a 2000 Suzuki SV650 with a 649cc V-twin 2 cylinder engine. Without question the 87 produced more power and gave better gas mileage.

That being said, I have only used 93 on my last 3 cars, which are a 2007 LS460, 2003 MB SL55 (I wouldn't dare put anything less than 91 in that, being supercharged with 500rwhp dynos), and a 1999 LS400. I question if the Lexus really needs 93 opposed to 87, but I do it just be sure as it's what the manufacturer recommends, and I figure there might be a small drop in performance and fuel economy so I stick with it. I don't drive but 6-8k miles per year, if I did 2-3x that then I might look into it more.

One thing I hate is that there is anywhere from 15 to 20+ cents between each tier of 87, 89, and 93. Before the gas crisis that happened like 10 years ago, the increments were pretty much ALWAYS 10 cents. You could count on paying exactly 20 cents more for 93 if the posted sign only listed the 87 price. A couple times I even caught a gas station charging literally 90 cents more over the advertised 87 price on the big sign; but you didn't find out the 93 price until you were already right in front of the pump. A clear case of price gouging.

 

If you motorcycle was optimized for regular unleaded then you will not see any advantage with premium. The power loss with premium is also to be expected and is more pronounced with motorcycles because they don't have advanced timing management for that vintage. Regular fuel is also more powerful.

If you use premium in a lawn mower it will stall or run poorly simple because the fuel changes the timing.
If you use premium in a car that is optimized for it then it will yield more power and fuel efficiency then if you used regular unleaded. It's as simple as that.

Using fuel not recommended or required by the manufacture will actually reduce the economy of the vehicle. If there is a plan to save money by buying cheap gas the savings will get negated somewhat by the loss of miles per gallon.

 

How much clearer can we make it? NOBODY IS SAYING PREMIUM CREATES MORE POWER!

 

Well, one thing cannot be denied. Many owners use 87 octane fuel in LS's that state premium only and I have never seen a thread where an owner has complained of knocking thanks to the great sensors and timing adjustment the ECU makes. Premium is "required" because the LS has a high compression engine. This is why Lexus and other brands state premium only. But if running 87 does not produce knocking conditions then it won't hurt the engine.

It's pretty simple. If you don't get knock when running lower octane then don't worry about it. If you do then you should worry about it. The LS400, 430, and 460 don't knock when running 87 octane. And yes, in a high compression engine higher octane does = more power and efficiency because it allows the timing to advance. This is particularly true of vehicles that have been tuned to a certain octane. With lower compression engines it's pointless to run higher octane fuel altogether. This is essentially what the octane rating is. It's resistance to pre-detonation on the compression stroke.

 

You can't always hear knock. And we've seen that timing gets pulled more aggressively and under more conditions with 87 octane, so some knock must be happening, even if the computer addresses it before it gets severe enough to hear.

Knock happens often in all engines but it's still bad and should be minimized to the extent possible to maximize engine life.

 

Just to add to what Dal said and then I'm out.
Dal is correct, knock happens even when using premium fuel. Knock creates harmonic vibrations that shorten the life of all motors regardless of what fuel you use. Each manufacturer tries to limit the amount of knock the car sees in all conditions but it's not perfect with current technology however they know through simulations with the recommended fuel how to tune it to last last longer. When you take the car closer to the edge of knock you have now introduced a condition where the engine life will be shortened. Shortening the engine life due to higher levels of knock frequency is not always perceivable but it will manifest in other areas and cause loose tolerances that lead to a noisy engine over time not to mention a reduction in power, economy and general health of the motor.
All engines become noisy due to excessive clearances over time due to wear and knock.

Even if you don't believe knock is not a problem consider that your .20 cents savings at the pump does not translate to it's full savings. The car will get poor gas mileage that will narrow whatever savings you are trying to achieve. So not only did you lose power you lost economy and emissions.

 

Unfortunately, in the case of gasoline you get what you pay for: the higher consumer premium gas has additives that resist separation and driers that remove water. If you live in an area that has high performance cars you can find pump gas >100 octane. If you choose lower octane gas there are cars built for that condition. 1990 Corolla is about 9:1. Corvette z06, Gallardo and Aventador have compression ratios at 11.1, 12.5 and 11.8 respectively. Lexus 460 is at 11.8. Nascar engines are limited to 12 and get fed ye' ole' 110. A significant computerized "adjustment" has to take place to run a car on 89 octane*.

Compression ratio = Octane
5:1 =72
6:1 =81
7:1=87
8:1=92
9:1=96
10:1=100
11:1=104
12:1=108

*some details have been left out to avoid confusion

 

I wanted to stay away from this conversation but misleading statements like the one above really gets under my skin.

The worst thing about the internet is misinformation seems to spread faster and further than good information. Totally erroneous statements like the one by superdenso above repeated so many times completely overwhelm reality and become their own reality.

Basic chemistry:
It is impossible to ignite fuel without heat and AIR.

Engine can have 100:1 compression and fuel will not ignite without AIR.

Google “stoichiometric air to fuel ratio” and you will see that maximum power comes at 12.5 air-to-fuel ratio and maximum efficiency is at 17 air-to-fuel ratio (not to confuse with compression ratio).

Engine comes with a throttle, without throttle engines are useless. Delaying/advancing timing will not make car drive. Throttle comes first, what throttle does? It controls AIR.
Throttle has 3 main positions:
Idling range
Cruising range
High power range

Rich mixtures are less efficient, but produce more power and burn cooler, which is kinder on the engine.

For acceleration and high load conditions, a richer mixture (lower air–fuel ratio) is used to produce cooler combustion and thereby prevent detonation.

Here is statement from Mazda:
2014 Mazda 3.
Mazda plans to achieve 30 percent increase in fuel economy by improving the internal combustion of the Skyactiv 2 engines. More specifically, the Skyactiv 2 engine's compression ratio would be bumped up to 18:1 from a current level of 13:1.Jan 6, 2014

Edit: Mazda 3 doesn't require premium fuel.

 

Just to add to my previous post. Direct injection made a lot of things possible fuel is no longer added through valves there is no fuel to detonate, fuel is added at the latest moment just when it suppose to ignite. Some car manufacturers also experimented with adding more fuel after initial ignition happened we will see how that goes.