Do you "have to" put high grade gas in this car?

[radioouman]

Originally posted by: nsafreak
Using anything less than premium gas in an 8 cylinder engine is typically not a good idea. You might get away with it but there's a chance you will see a decrease in performance and gas mileage as well.

Really? I put regular gas in my 1994 5.2 liter V8 because the manual says to.

 

[Metron]

I haven't seen a correct response yet...

The manufacturer is required by the EPA to recommend the grade of gasoline used during the EPA testing for emissions and mileage... their company lawyers won't let them list anything else. Otherwise, the company would void the results of their emissions and mileage testing.

Most modern electronic ignitions / computers will retard the timing to allow any grade of gas to be used. Idiotic warnings that your high compression engine will "... EXPLODE..." are specious.

Now, for my own possibly atypical experience:
I ran 87 octane regular unleaded in a 4.0 liter V-8 clearly marked "91 Octane Premium Only" for years, and the only result I got was BETTER mileage at a lower cost. Engine never exploded, and I never heard a single ping. Good luck to the rest of you marketing victims.

 

[FoBoT]

RTFM

 

[FoBoT]

Originally posted by: MotionMan
I know what the manual says. I do not believe everything they say in the manual.

:Q



RTFM

 

[mercanucaribe]

Originally posted by: thomsbrain

Originally posted by: nsafreak
Using anything less than premium gas in an 8 cylinder engine is typically not a good idea. You might get away with it but there's a chance you will see a decrease in performance and gas mileage as well.

care in to impart your wisdom on why some arbitrary number of cylinders is the end-all be-all of gas grades?

BTW, plenty of engines sense the grade of gas and accommodate it. using a lower grade results in less power, but with a 4.3 liter V8, and knowing lexus drivers, he'd never notice the difference. the question of why he cares is still valid, though. he's driving an expensive car that gets crappy mileage, and he cares about a buck or two per fill-up?

You'd get WORSE gas mileage with the lower octane gas... and it's harmful to the engine in the long term from what I've heard. Remember that the engine is fundamentally changing one of its operating procedures to use the lower octane.

By the way, octane is not "grade". There's no such thing as grades of gas-- that's just marketing. The higher octane is not higher quality. It just has more of the octane increaser to make it harder to burn so it can handle high compression.

 

[sswingle]

Use pure hydrogen. It worked for the mythbusters.

 

[ultimatebob]

What does the Lexus manual say, anyway? If it's like mine, it probably recommends 91 Octane but says that you can run 89 or even 87 octane with "reduced performance". I've run my car on 89 before, and it doesn't complain about it at all.

 

[Exterous]

IRL a series of pre-flame reactions will occur in the unburnt 'end gasses' in the combustion chamber before the flame front arrives. This is what causes the engine to 'knock' The octane rating refers to the fuels ability to resist the so called 'autoignition' to occur. "Autoignition can result in a loss in power and potential overheating.

Using a higher octane fuel will not improve your fuel economy unless you are not using the proper octane - which I can only assume is what is recommended in the manual. I cannot imagine in this day and age that a company would not advertise using the fuel that will give it the best MPG rating.

Something else of note: Older cars benifit from higher octane due to engine wear and the suseptability (sp) of engine 'knocking'. This knocking can actually lead to engine stalls due to loss of power. However, lower octane is particularly useful in winter months due to its increased combustion potential -> easier to start in cold weather

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

 

[Exterous]

Originally posted by: ultimatebob
What does the Lexus manual say, anyway? If it's like mine, it probably recommends 91 Octane but says that you can run 89 or even 87 octane with "reduced performance". I've run my car on 89 before, and it doesn't complain about it at all.

Its not the optiumum fuel because your car is optimized for 91. This can include loss of engine power or fuel efficiency - but it may not be noticeable. Would you really notice if you lost 2-5hp?

 

[imported_Baloo]

Originally posted by: nsafreak
Using anything less than premium gas in an 8 cylinder engine is typically not a good idea. You might get away with it but there's a chance you will see a decrease in performance and gas mileage as well.

It has nothing do with the number of cylinders, rather, it's the compression ratio. The higher the compression ratio the higher the octane gas necessary. Don't make the mistake of deciding what octane to use based on the number of cylinders. Eight cylinder engines on average have lower compression rations than 4 and 6 cylinder engines, and less oftan require premium gas. If one uses premium in an engine designed for regular, the fuel will not burn as completely, which will yield lower gas mileage and higher emissions, and lower horsepower. If one uses regular in a high compression honda civic 4 bangor, for example, that will yield pre-ignition, AKA, pinging, which can damage the pistions over time and reduce performance.

 

[Pepsi90919]

rocket fuel only

 

[Reckoner]

If you can afford a lexus, then you should be able to afford premium gas. If you can't, then you have larger problems than what grade of gas to choose.

 

[MotionMan]

http://www.fuelsaving.info/fuels.htm

Check out the footnote at the bottom regarding EUR vs. US Octain ratings.

MotionMan