rscharf

What are people's thoughts on the level of octane you should put in your car. I know that Lexus states premium. Do you think it's really necessary? If it's just a performance issue, but doesn't "hurt" the engine, I think I'd just put 87 octane in it (when I get it).

Thanks.

Robert

futuregs

mmm no, if your gonna put 87 octane in it, you minus well throw in some sugar each time you fill it up. 87 octane leaves horrible buildup in your tank after awhile and isn't THAT good for a car designed to run on premium. Lexus doesn't make money off the type of gas it's cars require, so it isn't like they want you to only put in premium. THere cars are built to perfection (almost) and therefore there parts need the newest and best gas to keep them running.
For instance if you had the option of turboin your car either twin turbo or single turbo. You wouldn't choose single, or at least I hope not. Unless the single is running more boost, but lets pretend it isnt. =]

Black94RX-7TT

That was a full of **** answer if I ever heard one.

87 octane will not leave a buildup in your tank.

The real reason is because these engines have high compression ratios, and need the extra octane to avoid detonation. I'm sure these engines will *tolerate* substandard fuel, but it will decrease the life of the engine, and will probably cause it to make nose, espescially under heavvy load. If you're at a high altitude you might be able to do it with no ill effects due to the decreased density of the air, but I don't know how high you'd have to go before it wouldn't be a problem.

This brings up an interesting question...does the ECU alter the cam phasing via the VVT-i system enough to effectively lower the compression? Anybody know?

LexFather

If u do not use the recommended fuel, you will recieve engine performance and fuel economy below what it is capable of.

Not only use premium, add some fuel injector cleaner every once in a while too.Was the really necessary?

Lower octane fuel will not burn as efficently as higher octane fuel so OVER TIME, if you don't maintain your car, it can happen (deposits buildup).

I agree with both of ya'll.

Black94RX-7TT

Yes, it was really necessary. He said that lower octane fuels cause buildup in the TANK. How lame brained is that?

Lower octane fuel doesn't burn as efficiently? That's a new one too. The octane rating only specifies the threshold at which combustion begins. Once combustion has begun, there is plenty of energy to continue the process to completion.

2SAVVY

Really thou like Gene said you pay huge dollars for your SC430.. I paid a touch under six figures (Ok its Canadian Monopoly Money) but its still expensive..

Like the owners manual says your car will run at reduced performance if you had to use lower octane in a pinch but why anyone would go out and purposely buy lower octane fuel to save a few bucks is beyond me.. If you are leasing your car then I know some of my friends are buying low octane and just doing the minimum maintenance just because they don't care and their outlook is "I'm just going to get a new one in 2-3 years anyways".. As a car guy this hurts me to no end.. Thus another reason why I don't buy cars that come off leases..

In the end its your car and you can do whatever you want to it.. We're just looking out..

LexFather

Oh hell, I guess I am a fine one to talk. Okay, well that is some crap I read in some magazine. Did not say it was the Bible or anything. Just my 2 cents.

LexusFamily

Using too low an octane on an engine designed for higher octane can be bad especially on a hot day and/or high speed run. Octane is a measure of the volatility of the gasoline. High performance engines (high compression ratios, aggressive timing, etc.) require high octane (lower volatility) so that the combustion event takes place in a controlled and useful manner (flame front propagates smoothly). If a low octane fuel is used, knock can occur. This knock results from an uncontrolled, violent ignition of the air-fuel mixture and stresses the engine out in the form of ultra high cylinder pressures and temperatures. Hence, it is bad for the engine. It is interesting to note that there is less potential energy in higher octane fuels. For example, using high octane in a Toyota Echo (a car that doesn't require it) will actually result in lower gas mileage than using regular.

I don't know what the SC430's ECU does specifically with the VVT. However, in general, I know a conventional strategy to safeguard against engine knock (which can be caused by using too low an octane) is to place knock transducers (essentially microphones) screwed into the engine block to listen for knock. When knock is detected, the ECU retards timing to lessen/eliminate it. (Additionally, if the engine is turbocharged, the ECU may reduce boost.)

I too would agree with the consensus. If you laid down the big bucks for a nice car (which the SC430 is), why try to save a few pennies and sacrifice engine performance and perhaps even longevity on getting "regular." It does not make sense.

rscharf

Alrigghhhhhty Then!!!

I get the message! :eek: I didn't know I would stir up such a firestorm with this question, but appreciate all the responses, and feel I better understand the issue now. I realize it sounds like pinching pennies after shelling out so many clams for the SC. Get it, shelling out clams, so sorry, I know its a bad... bad... attempt at humor. Just wanted some opinions after reading from one source that said although car manufacturers may suggest premium, that it's not really necessary. But I know better now, at least in respect to the SC.

So, Cadillac says that my 2000 DeVille is the first car of theirs they have suggested you can run with regular fuel. Do they want that Northstar engine to die prematurely so that I'm back in their dealership for another? I'm assuming that the Northstar 300 hp engine in my DTS would be considered a high performance engine, and with what has been posted here, should run on premium fuel!?!

Thanks again for all the comments.

Robert

LexusSC430

I think using regular in such a car as a cadillac wont harm it because I am sure its been made in accordance with the fuel. Camrys use regular because HP isnt the first thing on peoples minds and shelling the money out for premium fuel, while it would help performace is ridiculous in such a car. I know I can tell the difference if you bring my car back with regular versus premium...I know because my sneaky sister tried it once before.

The SC "I would" say has knock sensors, it would probably trip a light if you were regularly putting low octane in your car and driving it hard. If you drive it easy then there shouldnt be a problem in using the fuel. But when that engine starts spooling at 6000 rpms and it needs that air and fuel and the airs is reaching but the fuels is disappating whereas the high octane would handle the temperatures.......well you get my drift.

The premium fuel is for optimal performance....if you wanna drive Ms. Daisy around go but some 87 octane from Larrys Gas shop. I only put Sunoco 94 in the SC, because well....drive it like you stole it right???

Black94RX-7TT

I read up a bit on the 2000 DTS engine, and found that they lowered the compression ratio that year, and probably did a bit of tuning in the ECU. That's why it doesn't require premium. If it did require premium (higher compression, agressive timing, etc), then 330-350 wouldn't be out of the question for that engine.

futuregs

Ok lets get something straight, you wanna start ***** go to accordclub.com
2nd fo all don't tell me if was a no brained answer especially if it's happened to me. So how about you shut your mouth.

dequina

Has anyone put a 100 or 110 Octane rated gasoline in their SC 430? If you did, what kind of specific performance did the Sc 430 give?

Pearlpower

iTrader: (2)

Funny you should ask. A local 76 has 100 and I have been planning to see what if any benefits the SC would realize with such juice. Perhaps later this week. I did notice an improvement in my GS4.

rominl

iTrader: (4)

well putting in some to pump up the 91 rating to 93 or 94 will help

but pure 100, i am not sure if you are going to gain anything except some weight in your wallet