What octane gas do you use? (The Mother thread)
01-23-11, 01:52 PM
#121
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I use 91, I use to work at a Toyota dealership. My service manager said "Its really good to run premium gas every 2nd - 3rd fill up when over 300k on any car" but always run premium is the car says so. Im a new LS400 owner and running 91 not even sure what the old owners ran
01-23-11, 01:57 PM
#122
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I use 91, I use to work at a Toyota dealership. My service manager said "Its really good to run premium gas every 2nd - 3rd fill up when over 300k on any car" but always run premium is the car says so. Im a new LS400 owner and running 91 not even sure what the old owners ran
01-23-11, 03:23 PM
#123
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As noted by the previous posts it's silly to think higher octane gets better performance etc in most cases but here are two things to think about when buying your gas:
Older high performance engines DO need higher octanes. Case in point my 91 LS400 pings with 87 but runs fine on 89, there is no need for 93. However my 03 A6 with a 300hp 4.2L V8 is just fine with regular 87. I suppose the knock sensors etc are just better at controlling detonation.
Secondly one way an ECU can deal with detonation is dial back the timing... this = a little less hp. so technically you might get a little more HP but only because the engine is retarding the timing a tad to compensate for the knock. I imagine it's hardly noticeable and certainly not detectable by your "butt dyno"...
In short, run the lowest octane you can run without the engine pinging and save the $$$ for maintenance. Some cars will handle lower octane better than others.. in general it seems the newer ones handle it better than the older higher performance engines. Just get the gas from a decent chain like shell, mobil, hess, exxon etc etc etc
Older high performance engines DO need higher octanes. Case in point my 91 LS400 pings with 87 but runs fine on 89, there is no need for 93. However my 03 A6 with a 300hp 4.2L V8 is just fine with regular 87. I suppose the knock sensors etc are just better at controlling detonation.
Secondly one way an ECU can deal with detonation is dial back the timing... this = a little less hp. so technically you might get a little more HP but only because the engine is retarding the timing a tad to compensate for the knock. I imagine it's hardly noticeable and certainly not detectable by your "butt dyno"...
In short, run the lowest octane you can run without the engine pinging and save the $$$ for maintenance. Some cars will handle lower octane better than others.. in general it seems the newer ones handle it better than the older higher performance engines. Just get the gas from a decent chain like shell, mobil, hess, exxon etc etc etc
Ya better, b/c you're gonna need it. I never did understand why people put cheaper gas in when the price goes up. No matter how high gas prices are, you still only pay .20 a gallon more for 91 then 87 octane. It's less than $5.00 a tank. And if your car is running better and cleaner, which it is, then it's worth it. Some people put thousands of dollars into their cars for rims and all the extras (not that I'm against all that) and have their engine run like ***** b/c they want to save 
$5.00 a week in gas. That's my opinion.
01-23-11, 03:50 PM
#124
but the last two vehicles i seafoamed
94 nissan pickup @190km
02 mazda mpv @170km
had o2 sensor issues not long after, however the nissans was solved just by blasting it with carb cleaner a couple times but it ran a tad rich after (still better than lean)
but after this im kind of weary of seafoaming, i want to do it because in the end the reults are good but i might wait till a new sensor is in my budget incase
also has anyone ever heard of no smoke coming out after seafoaming, i did a buddies 240sx with 300km on it we expected **** tons of smoke and crap to come out but NOTHING did
01-23-11, 08:24 PM
#128
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have you ever had to replace o2 sensors?? i know it claims o2 sensor safe.
but the last two vehicles i seafoamed
94 nissan pickup @190km
02 mazda mpv @170km
had o2 sensor issues not long after, however the nissans was solved just by blasting it with carb cleaner a couple times but it ran a tad rich after (still better than lean)
but after this im kind of weary of seafoaming, i want to do it because in the end the reults are good but i might wait till a new sensor is in my budget incase
also has anyone ever heard of no smoke coming out after seafoaming, i did a buddies 240sx with 300km on it we expected **** tons of smoke and crap to come out but NOTHING did
but the last two vehicles i seafoamed
94 nissan pickup @190km
02 mazda mpv @170km
had o2 sensor issues not long after, however the nissans was solved just by blasting it with carb cleaner a couple times but it ran a tad rich after (still better than lean)
but after this im kind of weary of seafoaming, i want to do it because in the end the reults are good but i might wait till a new sensor is in my budget incase
also has anyone ever heard of no smoke coming out after seafoaming, i did a buddies 240sx with 300km on it we expected **** tons of smoke and crap to come out but NOTHING did
01-23-11, 09:08 PM
#129
Don't confuse octane with energy. Octane is just the rate that the fuel burns. If you live at higher altitudes you can get away with sllghtly lower octane. If you are burning premium gas in a car that does not require it ( the LS does require it) you are a fool and are just wasting your money.
Also if you never floor the gas pedal you may get away with lower octane
http://en.wikipedia.org/wiki/Octane_rating
in the Rocky Mountain (high altitude) states, 85 AKI is the minimum octane, and 91 AKI is the maximum octane available in fuel[citation needed]. The reason for this is that in higher-altitude areas, a typical naturally-aspirated engine draws in less air mass per cycle due to the reduced density of the atmosphere. This directly translates to less fuel and reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a carbureted car that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine
Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where octane is raised by blending in ethanol, energy content per volume is reduced.
When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure,
Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
Also if you never floor the gas pedal you may get away with lower octane
http://en.wikipedia.org/wiki/Octane_rating
in the Rocky Mountain (high altitude) states, 85 AKI is the minimum octane, and 91 AKI is the maximum octane available in fuel[citation needed]. The reason for this is that in higher-altitude areas, a typical naturally-aspirated engine draws in less air mass per cycle due to the reduced density of the atmosphere. This directly translates to less fuel and reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill up a carbureted car that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine
Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where octane is raised by blending in ethanol, energy content per volume is reduced.
When the throttle is partially open, only a small fraction of the total available power is produced because the manifold is operating at pressures far below atmospheric. In this case, the octane requirement is far lower than when the throttle is opened fully and the manifold pressure increases to atmospheric pressure,
Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
01-23-11, 11:00 PM
#130
01-24-11, 12:33 AM
#131
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WHAT?? Buy cheap gas and save $$$ for maintenance? Ya better, b/c you're gonna need it. I never did understand why people put cheaper gas in when the price goes up. No matter how high gas prices are, you still only pay .20 a gallon more for 91 then 87 octane. It's less than $5.00 a tank. And if your car is running better and cleaner, which it is, then it's worth it. Some people put thousands of dollars into their cars for rims and all the extras (not that I'm against all that) and have their engine run like ***** b/c they want to save $5.00 a week in gas. That's my opinion.
Ya better, b/c you're gonna need it. I never did understand why people put cheaper gas in when the price goes up. No matter how high gas prices are, you still only pay .20 a gallon more for 91 then 87 octane. It's less than $5.00 a tank. And if your car is running better and cleaner, which it is, then it's worth it. Some people put thousands of dollars into their cars for rims and all the extras (not that I'm against all that) and have their engine run like ***** b/c they want to save $5.00 a week in gas. That's my opinion.
And if your car is running better and cleaner, which it is, then it's worth it.
01-24-11, 10:17 AM
#133
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1996 LS400, 140K miles...I have always run regular and never hear any ping. A garageman told me that the auto companies test their cars on high test gas and therefore routinely recommend the usage of high test. I get about 25 mpg on IH driving.
01-24-11, 06:26 PM
#134
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