September 3rd, 2010 
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Question by Kawa_OoKami: How is premium unleaded gas good for your car?
Is Premium unleaded really good for your car?
I drive a Lexus Ls and it saids to use premium unleaded
but i just use medium unleaded.
Best answer:
Answer by rabatvilla
Its not. Waste of your money
Know better? Leave your own answer in the comments!
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Premium has a higher octane rating. A decrease in denotation or pinging while accelerating might occur rather than using gasoline that has a lower rating.
If your car recommends premium, you should use it. When the company calls for it, all the computer systems are set up to use it. It could affect your gas mileage and performance. Always use the grade of gas, that is called for.
They say you should only use high octane gas when you have a high performance V-8 engine. Cars like Corvettes, Mustang Cobras and so forth. Just remember also, when because it is a higher octane…it burns cleaner, which means you wont get as much depositing on the valves…making them ping less.
If the manufacture says to use premium and you don’t you are not getting the maximum power out of you car. There are knock sensors in the motor and if you running medium or even regular the computer will detune your engine to stop the knocks hopefully. In the winter I think you may be fine, it is in the summer that you really need the octane. Less than 10% of the cars require premium and I own 2 that do. In both i can tell a noticeable difference in performance as we have all accidentally once filled up with regular. Your call, but the computer can only detune so much and you may still have knocking and not even know it which will over time could hurt the engine.
The manufacturers have decided that your car REQUIRES a higher octane fuel. Chances are, the cheap gas you’re firing in your tank doesn’t burn right, robbing you of power as well as fuel economy…penny smart, dollar foolish. I have a Porsche 928S and I use premium because that’s what the engineers at Porsche get paid alot to determine, and intelligently so. You’ll start using premium after something goes wrong because you decided to cheese out rather than use what has been tried and true to be the right thing for your engine to burn. Better gas goes farther and warrants the minimal extra cost you pay at the pump for premium. Peace
premium has more octane (91) so it burns hotter and cleaner.
med. grade has (87) octane rating. med. grade will be fine.
What most are saying is true to a point yes you should use what your car calls for but if you don’t here’s the deal, normal driving in normal climates you will be okay with regular. Most of us don’t use the power in our V8 engines I know I don’t go around racing my Continental and I live in a climate where it doesn’t get very hot very seldom does it reach 90 degrees so regular is fine because the computer can compensate for the lack of octane. if you live in Arizona and have a heavy foot on the pedal a lot then you really need to use premium.
In the short run, it may appear to be ridiculous – but in the long run it will be of big help. Premium gas has higher octane rating, meaning less “knocking” effect. This in turn leads to better engine efficiency (more power) and less cost involved in maintenance. Again, you will only experience the advantage in a top-class car & not so much on a regular sedan.
JPGR has a great answer.
And especially if you live in CA where the gas is crappy 91 octane for premium.