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I know that the SC's require premium grade gasoline. But since 1992(year of my sc) the gas has gotten a lot better. The SC's compression ration is only 10.1 to 1. My friend runs mid grade on 11 to 1 compression ratio. He tells me that it wiould be perfectly fine to run mid grade in my SC. Is this true? The gas prices here just jumped 30cents a gallon and I am considering this option. Tell me what you guys think. What do you all run in your early year SC's?

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im not shure what grades ur talking about but i used to run 93 octaine now with gas up to 2.70 a gallon ii dropped to 87 octaine, and i could careless about car performance cause im broke.

but 87 is the same stuff. try mixing 87 with 104 octaine boost gives u a nice mix, cheaper.

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Premium = 93, Mid Grade = 91/90.....i dun wanna go down to 87 and possibly cause engine ping.

I always fill my tank up at 1/2 empty. One fill up is at 93 octane & the next is at 89 octane. Average = 91 octane, just what my owners manual says to use.

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Hummmmmmm! I just got my owner's manual out to see what it says about octane usage in my SC400. I have a 1992 SC400.

On page 172 of the owner's manual it says:

'Select premium unleaded gasoline with a Research Octane Number

of 96 (Octane rating 91) or higher. '

Which do I use when looking at the gas pump???

I think it is the Octane Rating, but I am not sure.

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  • 3 weeks later...
The owner's manual is from 1992 and gas is more refined then it was back then...91 octane back then was not near as good as 91 is today.

Good Evening,

Let's look at gasoline for a moment.

Octane is basically how long the fuel burns; higher number, burns longer, makes more horsepower. Lower number; burns faster, pings.

If your vehicle owner's manual specifies an octane rating of 87, running on gasoline with an octane rating of 89 or 91 or more will normally not make a difference.

However, there are some exceptions to this, and it must be noted that if the owner’s manual specifies using gasoline with an octane rating of 89 or 91, then that’s what you should use because that’s what the engine is designed and tuned for. Today's fuel is of higher quality, but 91 is still 91, just as 34 inch waist jeans from 1980 are the same 34 inch waist jeans today. It's a standard.

One - and a very important - exception is that when a vehicle gets older, the normal build-up of fuel- and lubricant-related deposits in the engine can increase the fuel octane number a car requires to prevent engine knock. For this reason, if a car more than a couple of years old experiences engine knocking, the problem may be solved simply by moving to the gasoline with the next-higher anti-knock index. This is backwards of what many people do.

Now, for the average SC400, a full tank is around 16 gallons. 16 X 2.50(regular) = $40. Then 16 X 2.70(Premium) = $43.20. So, for the price of a Happy Meal, you take the chance of damaging your Lexus.

Also, the Lexus maintenance schedules are based on the cleaning ability and quality of premium fuel. Using cheaper fuel means you'll not get the 60K miles from spark plugs, fuel filters, etc. And the thrill of a right foot cramp on the interstate just isn't as much fun.

Isn't that worth $3?

Good Luck B)

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Here. Here. :cheers:

Date the most attractive woman you can.

Don't drink cheap booze.

Buy a friend dinner.

Don't talk :censored: "It is better to remain silent and thought of as a fool, than it is to open ones mouth and remove all doubt"

Take a vacation every year.

Don't take yourself so serious.

Try to learn something new everyday.

Never feed you Lexus less than 89 Octane.

Words of wizdom given to me by my mother.

Dad said "don't bring that *BLEEP* around here"

Go figure.

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ya, i have to agree with 2xlex on that, octane rating is a set standard, and to awnser lextasy4's original question- if the factory recommends it just do it. heres why

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

the whole article is on http://www.howstuffworks.com/ just type in octane into the search bar

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