megamarine

Ok guys, I know this sounds ridiculous, but I need you guys to prove that Premium gasoline is better then Pure Unleaded gasoline. My dad currently owns a 1995 SC300 and refuses to put in Premium because he says there is no difference. Now, I know for a factor there is, but he won't take my word for it. He's more stubborn then I am! Anyways, he said if I could get people to prove there is a difference for the SC300, he'd start putting Premium in his tank.

Can you all do me that huge favor? Cause I can't stand to see that car ruined.
-Matt

RANDY P

the car is slightly detuned to compensate for lower octane gas. To an extent it doesn't matter until you beat on the car or run it under harsh conditions. They make the car so it won't self-destruct if you run it on bad gas (like in Mexico)

If it runs noticably worse on regular unleaded, then don't run it.

To know for certain if it makes a difference or not, next time you take a long trip, fill up with regular and measure the mileage then switch to super when you're almost empty. I'll bet you get better gas mileage on Super like the car was designed for.

On some of my cars it's worth 3 MPG, on my S10 truck it makes no difference at all.

Guess which car runs on regular and which one gets super.

95silversc

The fuel used needs to be stable and reliable in the engine. Cars running boost need premium and better for the same reason. Gasoline is pretty volatile and will explode without a spark if the engine is really hot, running a lot of compression or boost. Higher octane raises the point at which it will explode without a spark. So does methanol/water injection. Some boosted cars run e85 or c16 instead of gasoline because they are much more stable than gasoline in an engine. These fuels are like the equivalent of 120-140 octane.

Ive got the same year sc300 as ur dad. Ive got a 5speed and drive the **** out of my car. I always fill up with premium. High octane gas is for engines with higher compression like my sc300. A 1995 sc300 like mine and ur dads has a 10:1 compression ratio. Thats fairly high. I dont like to run with much higher compression than that on pump gas. I live in texas and run my engines up to the redline alot. On a hot day if I was beating on my car having fun out on some twistie I could prolly get some detonation at high rpm after a while.

QwkSC

iTrader: (1)

Your engine has this wonderful device called a knock sensor that prevents it from being damaged by lower octane fuels.

However you will lose power and fuel economy.

BostonSC4

iTrader: (2)

^^ what he said. the warning sign in the dash, and inside the fuel door was not put there so the lexus designers could go "hee hee hee lets see how many people we can screw out of buying cheap gas" the engines are veryy high compression motors. so, with that said here is what i believe happens with too low octane fuel.

as the piston goes up and down, fuel is injected into the chamber, as the piston comes up, the fuel should combust and complete the cycle. now, if your fuel is too low, for example regular 87 octane fuel...when the piston comes up, the fuel does not combust right away, it blows up too late because it is not reactive enough. the piston slams. creating a KNOCK. knocking is awful for the engine and causes problems. luckily for us, our cars have a knock sensor. your dad's knock sensor should be getting paid over time.

put in premium fuel!! lol its 10 cents more! maybe 20 cents more...in total probably not more than 5 dollars more to fill up than regular. its worth it. the car likes good food just like we do.

Black Fire

The amount of money you save by filling up with regular is so minimal, spend the few extra cents.

1KhpWrx

iTrader: (7)

I would never run anything less than 91 in any lexus

tavarish

iTrader: (2)

Here's the deal, if the manufacturer recommends premium, use premium. If they recommend regular, use regular. Easy.

Lexus cars use premium because the engines are tuned to utilize higher octane. Will the car run on 87? Sure. BUT you will have more unburned gas, poorer fuel economy, and decreased performance with the potential for engine damage if the knock sensor craps out down the road.

horent135

iTrader: (10)

But those extra cents can add up every week that you are at the gas pumps.

tavarish

iTrader: (2)

If it makes that much of a difference, don't buy a Lexus. Get a Honda and be economical. No point in buying a Lexus just to cheap out on the one thing that the car runs on.

It's like me buying $2k rims and buying Wanli tires. Doesn't make sense.

BostonSC4

iTrader: (2)

could not have said it better myself. treat the car right and it will treat your right. besides, if you had a sign on your saying "quality food only please" and everytime you got fed left overs from 3 weeks ago, wouldn't you get angry?

Enigma8246

They both have their benefits and drawbacks. Let him read this and decide for himself. I alternate premium and mid because even though i can probably afford the premium all the time, i'm habitually cheap and its a psychological thing

http://auto.howstuffworks.com/premiu...y-vehicles.htm

topdog849

iTrader: (1)

i put 89 octane all the time, im a cheap college student so every penny i save just goes back into my car for something else. the only time i put premium is if someone else is paying for my gas and even then i feel absolutely no difference.