Ownership Experience - 200t Premium vs Regular Fuel
#61
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I guess we should be glad we don't need diesel fuel in our Lexus vehicles !
Years ago I had a couple diesel vehicles...when diesel fuel cost much less than gas, especially in truck stops.
I had a VW that got about 40 MPG and over 50 on long trips.
What happened to the cost of diesel !
Years ago I had a couple diesel vehicles...when diesel fuel cost much less than gas, especially in truck stops.
I had a VW that got about 40 MPG and over 50 on long trips.
What happened to the cost of diesel !
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#62
The pursuit of F
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Fuel prices in Canada may be at the lowest we’ve seen in years, but it can still be tempting for consumers to save even more at the pumps by opting for a regular unleaded gasoline rather than topping up with the premium stuff. This can be especially attractive since the average motorist isn’t really clear on the difference, or if there even is one.
Many drivers understandably make the assumption that if premium fuel costs more and has higher octane then it must be better for their engine, or at the very least more refined. Perhaps it contains more energy or will make your vehicle run more efficiently. The answers are in fact no and not necessarily. Regular octane in Canada generally falls between 87 and 89 with premium normally being offered at 91, or even as high as 93 at some stations. Octane ratings are measured in anti-knock index values (AKI) which determine a gasoline’s ability to resist knocking or pinging during combustion, not the cleanliness or purity of the fuel in question.
The main difference between regular and premium gasoline is that fuel with a higher octane is able to withstand more compression before detonating. Octane levels depend on the blend of hydrocarbons used to make the fuel, along with the additives the fuel contains, both of which depend on where the crude came from, how it was refined and the grade of gasoline being produced.
Engines can be designed and constructed with an infinite number of variables depending on investment and their intended purpose. The small displacement engine in a thrifty econobox has likely been designed with cost perimeters and fuel efficiency in mind, while the supercharged V10 shoehorned into the engine bay of a performance vehicle has been optimized for just that – performance. Each will feature compression ratios and design attributes specific to the intended prowess of that powerplant.
Luxury and/or high performance vehicles have been specifically manufactured to run on a certain level of octane and therefore have a higher compression ratio, meaning that they are more susceptible to pre-ignition when the wrong type of fuel is used. Higher compression ratios correlate to higher engine performance and thermodynamic efficiency under ideal conditions. Essentially engines that have been optimized for higher octane fuel are able to extract more power from it than an engine designed to run on lower octane fuel.
Modern premium vehicles will feature anti-knock sensors, so even if you were to fill up with the wrong fuel, it wouldn’t do much, if any, damage to the vehicle’s internals on a limited basis.
Consistently putting regular fuel in a vehicle that requires premium could nullify your warranty however, which isn’t worth the prospect of the limited savings achieved by skimping at the pump.
Modern engines equipped with knock sensors will compensate by signalling the engine management system to retard spark timing. Activation will prevent knock but also decrease performance and result in poorer fuel economy.
“It is always better to go with the recommended octane level based on the manufacturer’s recommendation,” says Shell Canada fuel technology group Scientist Arjun Prakash, “The advantage of a higher octane of fuel is better performance, but that depends on vehicle make and model.”
So ideally you shouldn’t run regular fuel through an engine designed and optimized to run on premium, but conversely is there any benefit to putting premium fuel in a vehicle designed to run on regular? There doesn’t seem to be substantial or compelling evidence that there is enough value to offset the investment. Prakash contributed to a scientific research study intended to discern whether the octane response of premium-recommended, rather than premium required, vehicles differed depending on the fuel used. In theory, a lower octane fuel could result in less power while a higher octane one can be run at a higher ignition advance and therefore benefit from higher torque values.
Two gasoline fuels featuring AKI values of 87 and 91 respectively were put in five premium-recommended vehicles equipped with knock sensors to be tested for both acceleration and power output. Acceleration times and power at wide open throttle were read and recorded using a dynamometer. The findings were published and presented at a SAE International conference, a US-based, global professional association and standards organization for engineers.
After being analyzed and assessed to be sound, the results indicated that some of the vehicles were in fact more sensitive to octane levels than others. On an average, 91 octane fuel performed 1-2% better than the 87 octane gasoline. So, premium fuel will improve the performance of a vehicle calibrated for multiple levels of octane, but only marginally.
Premium fuel will feature additional additives but will not bring any significant performance benefits unless it has been calibrated to perform with higher octane. Rather than wasting money by adding premium fuel to a vehicle that doesn’t require it to potentially experience nominal to non-existent performance gains, opt for the level of octane listed in your owners’ manual and invest the savings in aftermarket parts that will actually enhance the performance of your car.
While premium fuel doesn’t add power to your vehicle, Prakash claims that the additives in premium fuel such as Shell’s VPower have shown to remove carbon deposits from injectors that could rob your vehicle of performance over time.
This brings us back to the original question of whether or not you really have to use premium gas. Realistically you only need to buy premium fuel if your vehicle asks for it specifically. If you can afford to buy a luxury or high performance vehicle, save your pennies elsewhere and don’t skimp out on the premium fuel. In most other cases you can likely use regular fuel without any noticeable issues aside from undetectable losses in performance and fuel mileage. Bottom line, dust off your owner’s manual and follow the specific instructions for your particular vehicle and do some research prior to purchasing a new one if you care that much about fuel prices.
Many drivers understandably make the assumption that if premium fuel costs more and has higher octane then it must be better for their engine, or at the very least more refined. Perhaps it contains more energy or will make your vehicle run more efficiently. The answers are in fact no and not necessarily. Regular octane in Canada generally falls between 87 and 89 with premium normally being offered at 91, or even as high as 93 at some stations. Octane ratings are measured in anti-knock index values (AKI) which determine a gasoline’s ability to resist knocking or pinging during combustion, not the cleanliness or purity of the fuel in question.
The main difference between regular and premium gasoline is that fuel with a higher octane is able to withstand more compression before detonating. Octane levels depend on the blend of hydrocarbons used to make the fuel, along with the additives the fuel contains, both of which depend on where the crude came from, how it was refined and the grade of gasoline being produced.
Engines can be designed and constructed with an infinite number of variables depending on investment and their intended purpose. The small displacement engine in a thrifty econobox has likely been designed with cost perimeters and fuel efficiency in mind, while the supercharged V10 shoehorned into the engine bay of a performance vehicle has been optimized for just that – performance. Each will feature compression ratios and design attributes specific to the intended prowess of that powerplant.
Luxury and/or high performance vehicles have been specifically manufactured to run on a certain level of octane and therefore have a higher compression ratio, meaning that they are more susceptible to pre-ignition when the wrong type of fuel is used. Higher compression ratios correlate to higher engine performance and thermodynamic efficiency under ideal conditions. Essentially engines that have been optimized for higher octane fuel are able to extract more power from it than an engine designed to run on lower octane fuel.
Modern premium vehicles will feature anti-knock sensors, so even if you were to fill up with the wrong fuel, it wouldn’t do much, if any, damage to the vehicle’s internals on a limited basis.
Consistently putting regular fuel in a vehicle that requires premium could nullify your warranty however, which isn’t worth the prospect of the limited savings achieved by skimping at the pump.
Modern engines equipped with knock sensors will compensate by signalling the engine management system to retard spark timing. Activation will prevent knock but also decrease performance and result in poorer fuel economy.
“It is always better to go with the recommended octane level based on the manufacturer’s recommendation,” says Shell Canada fuel technology group Scientist Arjun Prakash, “The advantage of a higher octane of fuel is better performance, but that depends on vehicle make and model.”
So ideally you shouldn’t run regular fuel through an engine designed and optimized to run on premium, but conversely is there any benefit to putting premium fuel in a vehicle designed to run on regular? There doesn’t seem to be substantial or compelling evidence that there is enough value to offset the investment. Prakash contributed to a scientific research study intended to discern whether the octane response of premium-recommended, rather than premium required, vehicles differed depending on the fuel used. In theory, a lower octane fuel could result in less power while a higher octane one can be run at a higher ignition advance and therefore benefit from higher torque values.
Two gasoline fuels featuring AKI values of 87 and 91 respectively were put in five premium-recommended vehicles equipped with knock sensors to be tested for both acceleration and power output. Acceleration times and power at wide open throttle were read and recorded using a dynamometer. The findings were published and presented at a SAE International conference, a US-based, global professional association and standards organization for engineers.
After being analyzed and assessed to be sound, the results indicated that some of the vehicles were in fact more sensitive to octane levels than others. On an average, 91 octane fuel performed 1-2% better than the 87 octane gasoline. So, premium fuel will improve the performance of a vehicle calibrated for multiple levels of octane, but only marginally.
Premium fuel will feature additional additives but will not bring any significant performance benefits unless it has been calibrated to perform with higher octane. Rather than wasting money by adding premium fuel to a vehicle that doesn’t require it to potentially experience nominal to non-existent performance gains, opt for the level of octane listed in your owners’ manual and invest the savings in aftermarket parts that will actually enhance the performance of your car.
While premium fuel doesn’t add power to your vehicle, Prakash claims that the additives in premium fuel such as Shell’s VPower have shown to remove carbon deposits from injectors that could rob your vehicle of performance over time.
This brings us back to the original question of whether or not you really have to use premium gas. Realistically you only need to buy premium fuel if your vehicle asks for it specifically. If you can afford to buy a luxury or high performance vehicle, save your pennies elsewhere and don’t skimp out on the premium fuel. In most other cases you can likely use regular fuel without any noticeable issues aside from undetectable losses in performance and fuel mileage. Bottom line, dust off your owner’s manual and follow the specific instructions for your particular vehicle and do some research prior to purchasing a new one if you care that much about fuel prices.
#63
Racer
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Good article, pretty much says what has been said in this thread all along in a kinder, gentler way.
Lexus manual says to use 91 or higher only so there is no choice other than 93 at the pump.
My area is the same as the photo in the article that shows a pump with 3 choices 87,89,and 93. I could not find any stations that sell 91. If 91 or higher is considered premium what is 89?- regular plus? Why do they sell it?
Anyway, I didn't want Corrado to feel alone here, so I have to admit I tried a tank of 89 and noticed no perceptible difference in performance or fuel economy. However, my next tank will be premium and there after.
Lexus manual says to use 91 or higher only so there is no choice other than 93 at the pump.
My area is the same as the photo in the article that shows a pump with 3 choices 87,89,and 93. I could not find any stations that sell 91. If 91 or higher is considered premium what is 89?- regular plus? Why do they sell it?
Anyway, I didn't want Corrado to feel alone here, so I have to admit I tried a tank of 89 and noticed no perceptible difference in performance or fuel economy. However, my next tank will be premium and there after.
#64
The pursuit of F
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^^^ Yeah, bottom line, lower octane should not be used regularly and only sparingly if no other choice at that time. Not worth the risk of prolonged use and ill effects.
#65
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Well, the reason for my post was just to get some real world experience with those that actually own a 200t engine.
I know the math and I've done research. It will be interesting switching to 91 after using 87 in my RX. In fact I don't recall ever owning a vehicle that didn't run on Regular. I should be trading in my RX this Thursday on a NX.![Woohoo](https://www.clublexus.com/forums/images/smilies/woohoo.gif)
I know the math and I've done research. It will be interesting switching to 91 after using 87 in my RX. In fact I don't recall ever owning a vehicle that didn't run on Regular. I should be trading in my RX this Thursday on a NX.
![Woohoo](https://www.clublexus.com/forums/images/smilies/woohoo.gif)
Here's a link to a Canadian website that compares the annual costs in gas of two or more vehicles.
http://oee.nrcan.gc.ca/fcr-rcf/public/index-e.cfm
I hope this helps.
#66
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I know Lexus recommends premium fuel (91+) for the NX turbo. Have anybody used anything higher than the recommended 91? Like Ultra 94 in Canada? Any differences?
#67
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Where I live there is 87, 89, and 93. I've been filling mine with 93 most of the time. I can't tell a difference between the blends at all. MPG has been constant. I'd say for every 4 tanks of 93 I put in one of 87.
#68
Lexus Test Driver
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When a company puts 91+, it means you can use 91, 93, 94 without an issue. Your car is tuned to work with a minimum of 91. If you use higher, there won't be any gain, it simply will use the 91 octane fuel tables and move forward. So no, you won't see any difference.
Just don't use below 91, or you will run into knock issues. Others have "claimed" its ok to use below 91, but until there is engine output data to show that the car can adjust timing to avoid knock, its best to do what the manual says.
Just don't use below 91, or you will run into knock issues. Others have "claimed" its ok to use below 91, but until there is engine output data to show that the car can adjust timing to avoid knock, its best to do what the manual says.
#69
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i'd be extremely weary about knocks.. i don't know if its the some knocks as you hear when you have exteremly low oil almost to none at all, but when you're running like that for a short period, you can say good bye to your engine.. my freaking tard father-in-law barrowed our '99 camry for four months and drove it until it was almost out of oil. i quickly changed the oil, but the damage was done. a week or two later, the piston short right through the oil pan while on the road. just do the right thing, avoid knocks.
#70
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I have been using 93 since in my area they have 87, 89, and 93 grades. My dealer and the 3 sales associates I worked with told me I could use regular because the ECU will adjust to the gas that is put in. They did mention that with regular you may not achieve the true power output of the engine and may see a difference in fuel economy. I don't think it will cause knocking but should produce a difference in engine performance.
#71
Lexus Test Driver
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I have been using 93 since in my area they have 87, 89, and 93 grades. My dealer and the 3 sales associates I worked with told me I could use regular because the ECU will adjust to the gas that is put in. They did mention that with regular you may not achieve the true power output of the engine and may see a difference in fuel economy. I don't think it will cause knocking but should produce a difference in engine performance.
Reduced power output comes from the requirement of the engine to pull timing to react to a lower octane of fuel. Do you know what else comes from the need to pull timing? Knocking.
The only way this doesn't happen is if the car has multiple tables. In which once you reach X degrees of timing, the car will jump tables and begin to add timing back under a different A/F ratio and compression ratio.
My genesis coupe back in the day said it was to run 316hp at 91+ octane, and 306 at below 91. Thus, the manual clearly stated that you COULD run lower octane. As far as I can tell (due to this forum as my car has not arrived yet), is that your are NOT given that option in the NX manual. Thus, it shouldn't be an option.
And like I said, if you run OVER 91, the car will remain in the 91 tables and just waste the extra octane. No harm going over, just hurtful to go down.
Last edited by Swacer; 04-30-15 at 08:32 AM.
#72
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From the Manual:
You must only use unleaded gasoline in your vehicle.
Select premium unleaded gasoline with an octane rating of 91 (Research
Octane Number 96) or higher required for optimum engine performance. If
91 octane cannot be obtained, you may use unleaded gasoline with an octane
rating as low as 87 (Research Octane Number 91). Use of unleaded gasoline
with an octane rating lower than 91 may result in engine knocking and significantly
reduced performance. Persistent knocking can lead to engine damage
and should be corrected by refueling with higher octane unleaded gasoline.
You must only use unleaded gasoline in your vehicle.
Select premium unleaded gasoline with an octane rating of 91 (Research
Octane Number 96) or higher required for optimum engine performance. If
91 octane cannot be obtained, you may use unleaded gasoline with an octane
rating as low as 87 (Research Octane Number 91). Use of unleaded gasoline
with an octane rating lower than 91 may result in engine knocking and significantly
reduced performance. Persistent knocking can lead to engine damage
and should be corrected by refueling with higher octane unleaded gasoline.
#73
Lexus Test Driver
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...
Reduced power output comes from the requirement of the engine to pull timing to react to a lower octane of fuel. Do you know what else comes from the need to pull timing? Knocking.
The only way this doesn't happen is if the car has multiple tables. In which once you reach X degrees of timing, the car will jump tables and begin to add timing back under a different A/F ratio and compression ratio.
...
And like I said, if you run OVER 91, the car will remain in the 91 tables and just waste the extra octane. No harm going over, just hurtful to go down.
Reduced power output comes from the requirement of the engine to pull timing to react to a lower octane of fuel. Do you know what else comes from the need to pull timing? Knocking.
The only way this doesn't happen is if the car has multiple tables. In which once you reach X degrees of timing, the car will jump tables and begin to add timing back under a different A/F ratio and compression ratio.
...
And like I said, if you run OVER 91, the car will remain in the 91 tables and just waste the extra octane. No harm going over, just hurtful to go down.
Lower octane fuel will increase likely hood of detonation, which in turn will increase knocking, to be detected by the knock sensors, and the ECU will then pull back timing to reduce or eliminate the knock. Once that timing is established, the engine will run happily, aside from the side effects of reduced performance.
The concern comes from the fact that the ECU always attempts to get the most optimal timing (based on fuel tables for 91 octane) by advancing timing, sensing the knock and pulling it back. That cycle is repeated over and over again, and in ideal scenario, the knock are few and far in between. What really happens is that aggressive drivers push the engine hard with sudden acceleration, and the knock frequency increases and volume increases before the ECU pulls back timing, thus leading to slow but increasingly steady damage. This is why you will hear of people never having issues using lower octane fuel, because they don't push their engine hard enough for knocking to be an issue, where as others have issues since they push their engines to the knock level and that can happen even with the right fuel if running the engine at redline consistently.
If
#74
Lexus Champion
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Most dealerships wouldn't want to scare away potential buyers with talk of premium unleaded during the sales process - But during delivery after the sale, it wouldn't hurt to cover fuel requirements with new owners before leaving the dealership.
#75
The pursuit of F
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@lsft, I've tried 94 from Petro Canada once in the NX and it felt slightly more lively, but to be honest, not sure if the placebo effect came into play.