SC300/400 owners ... are you still buying premium gas for your car?
#91
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93 on my SC and both GS3s. There is no compromise. Tried 87 on older GS way back when and it got pissed at me. It knocked like crazy. Same thing happened with the SC, which the previous owner had put in 87. Haven't and will not put it in anything less than 93 into the newer GS. Made it from Witchita Falls back to Houston with three people in the car, heater on, bags in the trunk doing 80mph with 1/4 left. Thats alittle over 500 miles. I only use the premo stuff.
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ANother thing is to stay away from the ethanol gas. You will burn the gas alot faster. I was told that all Mobil and Exxon gas station don't use it at all in there gas. I put Exxon in my 94 sc400 and it will last me 3 weeks before I have to refill. When i put gas it will only last 1 maybe 2 weeks.
#96
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What's up with the caps? You might not notice the little shake if there is one, if you wanna treat your SC like a beater then go ahead. It might not matter if your engine is going to die soon anyway.
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Many people won't understand what the difference is until they've had to clean the carbon build up in the intake and EGR system.
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On N/A cars (especially older, low compression designs) there is no discernible difference between high vs low octane. If an ECU doesn't detect enough knock to pull timing, there will be NO effect on power.
In modern high compression motors it can and DOES make a difference (I personally spent some time back in 2009 in a pre-production Corvette ZR1 that was being low octane tested) Many ECU's will pull significant timing in response to knock.
That being said, on my stock NA 2JZ I ran both. No difference that I noticed. My motor didn't blow up. Passing power was not affected. Ran nearly 220,000 miles without problems before the motor got swapped.
On my 1JZ? I'll only run premium![Smilie](https://www.clublexus.com/forums/images/smilies/smile.gif)
In modern high compression motors it can and DOES make a difference (I personally spent some time back in 2009 in a pre-production Corvette ZR1 that was being low octane tested) Many ECU's will pull significant timing in response to knock.
That being said, on my stock NA 2JZ I ran both. No difference that I noticed. My motor didn't blow up. Passing power was not affected. Ran nearly 220,000 miles without problems before the motor got swapped.
On my 1JZ? I'll only run premium
![Smilie](https://www.clublexus.com/forums/images/smilies/smile.gif)
#100
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And this. I typed a whole lot of stuff about carbon soot and all that then saw your post on page 2 explaining everything that goes on, pretty much the same tihs you said, LOL.
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ANother thing is to stay away from the ethanol gas. You will burn the gas alot faster. I was told that all Mobil and Exxon gas station don't use it at all in there gas. I put Exxon in my 94 sc400 and it will last me 3 weeks before I have to refill. When i put gas it will only last 1 maybe 2 weeks.
#102
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I was mixing it up, then did a full tank of regular. Did not like it at all my SC400 did not ping or anything like that, but fuel economy went down. Then tried mid a bit better but still was barely getting to 300mi a tank. So I'm back to premium. Feels like more power and better gas mileage to me.
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Team Lexus owners, in order to help with the confusion, I thought I would post up this explanation off another forum addressing this very subject...The thing to think about on our SC's is I do believe the factory manual states "Premium octane fuel is required", not recommended. Consider that the SC was considered quick and fast when it first debuted in 91, it was built as a performance vehicle...SO, does the factory ECU retard timing and knock enough to stave off all "pinging" or detonation when the car is under load? I do not know the answer to this...And I will never know on my V8, as the factory ECU is now gone. If you hear pinging when going up a hill, or acclerating, know that sound signifies minor damage to the cylinders over time...as well as decreased power, torque and fuel economy...And, as the explanation states below at the end, since the difference in the cost of regular and premium is about 5%, and the difference in fuel economy is about the same, you save no money, and you run the risk of shortening the life of your engine, as well as definitely losing performance. If you want to save...Just drive easy...![Wink](https://www.clublexus.com/forums/images/smilies/wink.gif)
Ryan
BMW explains using lower Octane gasoline
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Ryan
BMW explains using lower Octane gasoline
Straight from the BMW spokesperson, we get the final verdict regarding using 89 or 87 octane gas in our 91 preferred cars.
Running On Regular: Do Premium Vehicles Really Need Premium Gasoline?
From Stan Baldwin online
Long before gasoline rocketed through $4 a gallon many people were dismayed to see a significant percentage of their income disappearing into the tank of their car. Today, a wobbly economic outlook, increases in the cost of most other forms of energy, as well as the cost of life’s staples, have prompted folks to look for every possible way to cut back on spending. “Can I save money by running my car on Regular?” “Will it hurt the engine?” my friends ask. More than one person driving a car the manufacturer has spec’d for Premium has told me “I use Regular and my car runs fine.” Are there consequences of “down grading” your fuel? It is definitely a timely question, so we sent e-mail inquiries off to a half dozen manufacturers asking about their technology and their policy on the matter.
While waiting for their reply let’s review some internal combustion engine characteristics. Fuel does not truly explode in a cylinder, at least it isn’t supposed to. It burns smoothly, albeit very rapidly, across the cylinder. The octane rating is a measure of the propensity a given fuel has to burning, rather than exploding. Gasoline “exploding” in the cylinder is frequently called “detonation” or more colloquially, “knocking” or “pinging”. These explosions, because they happen as the piston is rising during the compression stroke and try to shove the piston back down the bore, can do damage over time. In the case of severely stressed motors, such as in race cars, a few seconds of serious detonation can destroy the engine. Two of the mechanical considerations affecting how smoothly a fuel burns are compression and cylinder head configuration. Two variable considerations of great importance are the temperature in the cylinder and the ignition timing. Every manufacturer designs and builds their engines to operate most efficiently for the application intended with a gasoline of a particular octane rating.
Not all that long ago, before the advent of engine management systems, the result of tanking up a high compression vehicle with standard grade fuel was immediately obvious. Providing the stereo wasn’t cranked up past 100 decibels, the pinging or knocking from the engine compartment let you know something was not right. Driving up a hill, towing a load or simply accelerating quickly produced an unnerving rattle from under the hood. It sounded very much like your carbureted V-8 had morphed into a diesel. Until the age of microprocessors enabled the creation of engine management systems, the consequence of a steady diet of low octane fuel could be fatal for a high performance engine.
General Motors, Honda, Toyota and BMW responded to our inquiry. Honda’s public relations representative declined to comment on the issue. Toyota noted that essentially all their current models are designed to run on 87 octane. I asked about using 85 octane, available in some markets, and Bill Kwong of Toyota corporate PR told me they would run fine, with maybe only a slight 2-3 percent decline in horsepower and fuel mileage. But 85 octane is usually only offered in markets at altitude (i.e. Denver, Colorado) where the reduced oxygen doesn’t allow an engine to reach full designed power in any event. If you drive a modern Toyota, the octane rating of your fuel isn’t much of an issue. But what about a brand aimed squarely at the performance market? What about BMW?
Thomas Plucinsky, BMW Product and Technology Communications Manager told us all BMW engines are designed to run on 91 octane. All performance testing, including EPA emissions and fuel mileage, is done with 91 octane. However, though BMW is all about performance, their motors will run on 89 or 87 octane without damage. The knock sensors pull the ignition timing back and eliminate detonation. There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels. One not so obvious concern, Mr. Plucinsky noted, is the type and quality of additives the gasoline companies include in the fuel. Premium gasolines may have better additive packages which are more effective keeping fuel systems (particularly injectors) clean and working efficiently, than those in regular grade fuels or off-brand products. Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line.
Dave Muscaro, Director of Engine Development/Calibration for GM power trains explained GM has “three flavors” of fuel specification for their offerings: Regular (87 octane) Recommended, Premium (91) Recommended, and Premium Required. Again, we are more concerned with the last two categories where regular could be substituted for the specified Premium. All the engines have a knock sensing ability that retards the spark when detonation occurs. For the premium recommended vehicles the spark advance will be pulled back enough to eliminate the detected knocking. The typical driver will not notice a performance decrease, except under load, and mileage will decline slightly. The engines intended for performance, such as the LS7 or the supercharged small block V-8, are Premium Required powertrains. The customers clearly were not primarily concerned with economy when they chose a performance vehicle and GM optimizes the engine management system to deliver the highest possible power output at all times. To this end the detonation control system does not retard the spark to the point required to prevent all knocking. It would seem a determined deranged drag racer could run Regular in his Corvette and, over time, he might manage to melt a piston or two.
If burning 87 octane in your car, when 91 octane is specified, will not harm the engine, and the performance degradation is not noticeable in typical driving, how much money can you save? The Energy Information Administration, U.S. Government Department of Energy, offers some figures for US gasoline retail prices (these are averages, all areas, all formulations). A year ago Regular was going for $2.982 a gallon and Premium was commanding $3.196 a gallon. The 21.4 cent difference delivered a 6.7 percent saving over Premium. This June 23, 2008, Regular extracted $4.079 from your wallet while Premium sucked up $4.312 for every gallon. The differential (23.3 cents) has grown slightly since 2007 but buying Regular is now only 5.4 percent cheaper than Premium. Since 5 percent is roughly the typical percentage of mileage decrease to be expected with the 87 octane fuel in a 91 octane engine, is there any savings at all?
Bottom Line: Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the immediate savings at the pump may be wiped out by the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time.
Running On Regular: Do Premium Vehicles Really Need Premium Gasoline?
From Stan Baldwin online
Long before gasoline rocketed through $4 a gallon many people were dismayed to see a significant percentage of their income disappearing into the tank of their car. Today, a wobbly economic outlook, increases in the cost of most other forms of energy, as well as the cost of life’s staples, have prompted folks to look for every possible way to cut back on spending. “Can I save money by running my car on Regular?” “Will it hurt the engine?” my friends ask. More than one person driving a car the manufacturer has spec’d for Premium has told me “I use Regular and my car runs fine.” Are there consequences of “down grading” your fuel? It is definitely a timely question, so we sent e-mail inquiries off to a half dozen manufacturers asking about their technology and their policy on the matter.
While waiting for their reply let’s review some internal combustion engine characteristics. Fuel does not truly explode in a cylinder, at least it isn’t supposed to. It burns smoothly, albeit very rapidly, across the cylinder. The octane rating is a measure of the propensity a given fuel has to burning, rather than exploding. Gasoline “exploding” in the cylinder is frequently called “detonation” or more colloquially, “knocking” or “pinging”. These explosions, because they happen as the piston is rising during the compression stroke and try to shove the piston back down the bore, can do damage over time. In the case of severely stressed motors, such as in race cars, a few seconds of serious detonation can destroy the engine. Two of the mechanical considerations affecting how smoothly a fuel burns are compression and cylinder head configuration. Two variable considerations of great importance are the temperature in the cylinder and the ignition timing. Every manufacturer designs and builds their engines to operate most efficiently for the application intended with a gasoline of a particular octane rating.
Not all that long ago, before the advent of engine management systems, the result of tanking up a high compression vehicle with standard grade fuel was immediately obvious. Providing the stereo wasn’t cranked up past 100 decibels, the pinging or knocking from the engine compartment let you know something was not right. Driving up a hill, towing a load or simply accelerating quickly produced an unnerving rattle from under the hood. It sounded very much like your carbureted V-8 had morphed into a diesel. Until the age of microprocessors enabled the creation of engine management systems, the consequence of a steady diet of low octane fuel could be fatal for a high performance engine.
General Motors, Honda, Toyota and BMW responded to our inquiry. Honda’s public relations representative declined to comment on the issue. Toyota noted that essentially all their current models are designed to run on 87 octane. I asked about using 85 octane, available in some markets, and Bill Kwong of Toyota corporate PR told me they would run fine, with maybe only a slight 2-3 percent decline in horsepower and fuel mileage. But 85 octane is usually only offered in markets at altitude (i.e. Denver, Colorado) where the reduced oxygen doesn’t allow an engine to reach full designed power in any event. If you drive a modern Toyota, the octane rating of your fuel isn’t much of an issue. But what about a brand aimed squarely at the performance market? What about BMW?
Thomas Plucinsky, BMW Product and Technology Communications Manager told us all BMW engines are designed to run on 91 octane. All performance testing, including EPA emissions and fuel mileage, is done with 91 octane. However, though BMW is all about performance, their motors will run on 89 or 87 octane without damage. The knock sensors pull the ignition timing back and eliminate detonation. There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels. One not so obvious concern, Mr. Plucinsky noted, is the type and quality of additives the gasoline companies include in the fuel. Premium gasolines may have better additive packages which are more effective keeping fuel systems (particularly injectors) clean and working efficiently, than those in regular grade fuels or off-brand products. Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line.
Dave Muscaro, Director of Engine Development/Calibration for GM power trains explained GM has “three flavors” of fuel specification for their offerings: Regular (87 octane) Recommended, Premium (91) Recommended, and Premium Required. Again, we are more concerned with the last two categories where regular could be substituted for the specified Premium. All the engines have a knock sensing ability that retards the spark when detonation occurs. For the premium recommended vehicles the spark advance will be pulled back enough to eliminate the detected knocking. The typical driver will not notice a performance decrease, except under load, and mileage will decline slightly. The engines intended for performance, such as the LS7 or the supercharged small block V-8, are Premium Required powertrains. The customers clearly were not primarily concerned with economy when they chose a performance vehicle and GM optimizes the engine management system to deliver the highest possible power output at all times. To this end the detonation control system does not retard the spark to the point required to prevent all knocking. It would seem a determined deranged drag racer could run Regular in his Corvette and, over time, he might manage to melt a piston or two.
If burning 87 octane in your car, when 91 octane is specified, will not harm the engine, and the performance degradation is not noticeable in typical driving, how much money can you save? The Energy Information Administration, U.S. Government Department of Energy, offers some figures for US gasoline retail prices (these are averages, all areas, all formulations). A year ago Regular was going for $2.982 a gallon and Premium was commanding $3.196 a gallon. The 21.4 cent difference delivered a 6.7 percent saving over Premium. This June 23, 2008, Regular extracted $4.079 from your wallet while Premium sucked up $4.312 for every gallon. The differential (23.3 cents) has grown slightly since 2007 but buying Regular is now only 5.4 percent cheaper than Premium. Since 5 percent is roughly the typical percentage of mileage decrease to be expected with the 87 octane fuel in a 91 octane engine, is there any savings at all?
Bottom Line: Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the immediate savings at the pump may be wiped out by the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time.
#105
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Ryan, thanks for the explanation. This discussion always reminds me of the chicken/egg debate- but for everyone who swears it won't do any harm, there's always at least one who experienced/knows someone who suffered catastrophic engine damage traceable to fuel.
Not worth the worry, in my opinion. Besides, and slightly more important- given that the youngest of these engines is now approximately 12 years old (mine's 15) and the oldest is 20 (almost legal) - don't we have unforeseen issues to worry about? Is it really worth it to take a chance on lower grade fuel if it leads to a major failure or combination elsewhere?
These cars are a blast to drive if you take care of them and treat them right.
Not worth the worry, in my opinion. Besides, and slightly more important- given that the youngest of these engines is now approximately 12 years old (mine's 15) and the oldest is 20 (almost legal) - don't we have unforeseen issues to worry about? Is it really worth it to take a chance on lower grade fuel if it leads to a major failure or combination elsewhere?
These cars are a blast to drive if you take care of them and treat them right.