I was considering buying an Acura RDX SUV and they were congratulating themselves for a one MPG increase by using the new cylinder shut-down system under low power conditions. The down side was the engine now Requires premium fuel. So my fuel purchases go up ~ 17.5% and I gain ~ one MPG on the highway but, no increase for city or combined. So they have a much more complicated valve timing cylinder head and a fuel requirement that goes from 87 to 91 octane. What were the engineers thinking when they did this foolish trade-off? Ed
What were they thinking?
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CAFE!!! Plain and simple.
Originally Posted By: Eddie
I was considering buying an Acura RDX SUV and they were congratulating themselves for a one MPG increase by using the new cylinder shut-down system under low power conditions. The down side was the engine now Requires premium fuel. So my fuel purchases go up ~ 17.5% and I gain ~ one MPG on the highway but, no increase for city or combined. So they have a much more complicated valve timing cylinder head and a fuel requirement that goes from 87 to 91 octane. What were the engineers thinking when they did this foolish trade-off?
Has the RDX not always recommended premium fuel? I know it did in the first generation (turbo 2.3L), and I'm sure it always has in the current generation (with the J35Y).
I'm not aware of any Acura that doesn't recommend premium fuel, actually. The Acura engines are usually tuned a little differently than the Honda engines, offering performance gains in exchange for premium fuel.
I was considering buying an Acura RDX SUV and they were congratulating themselves for a one MPG increase by using the new cylinder shut-down system under low power conditions. The down side was the engine now Requires premium fuel. So my fuel purchases go up ~ 17.5% and I gain ~ one MPG on the highway but, no increase for city or combined. So they have a much more complicated valve timing cylinder head and a fuel requirement that goes from 87 to 91 octane. What were the engineers thinking when they did this foolish trade-off?
Has the RDX not always recommended premium fuel? I know it did in the first generation (turbo 2.3L), and I'm sure it always has in the current generation (with the J35Y).
I'm not aware of any Acura that doesn't recommend premium fuel, actually. The Acura engines are usually tuned a little differently than the Honda engines, offering performance gains in exchange for premium fuel.
OVERKILL
$100 Site Donor 2021
Originally Posted By: shDK
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
I believe the same engine without cylinder deactivation in another Acura model only recommended premium fuel and not required it. I will confirm that. Ed
I don't know of any major fuel markets with standard 91 RON gasoline. 85, 86 are as likely as North America's 87.
It is un-questionably the mandated CAFE requirements since it also is Fleet-based ... In other words if half your sales are SUVs then your cars need better fuel economy to meet the Averaging requirements than if 20% are SUVs.
Premium / Luxury brands sell more SUVs thus they need all the MPG help they can gat ... A 1 MPG improvement might be the equivalent, fleet-wise, as a 5 MPG improvement in a light sedan or coupe model if uou sell a lot of the heavier models.
Remember it is mandatory to reduce fuel consumption by volume, but there is zero requirement to manage the *cost of ownership* so your net overall gas bill is completely irrelevant to meeting CAFE. What do you think is going to happen next?
It is un-questionably the mandated CAFE requirements since it also is Fleet-based ... In other words if half your sales are SUVs then your cars need better fuel economy to meet the Averaging requirements than if 20% are SUVs.
Premium / Luxury brands sell more SUVs thus they need all the MPG help they can gat ... A 1 MPG improvement might be the equivalent, fleet-wise, as a 5 MPG improvement in a light sedan or coupe model if uou sell a lot of the heavier models.
Remember it is mandatory to reduce fuel consumption by volume, but there is zero requirement to manage the *cost of ownership* so your net overall gas bill is completely irrelevant to meeting CAFE. What do you think is going to happen next?
I just confirmed that the same engine without cylinder deactivation only RECOMENDS premium fuel.
Originally Posted By: Eddie
I just confirmed that the same engine without cylinder deactivation only RECOMENDS premium fuel.
What are the two exact model years/model names were talking here?
I just confirmed that the same engine without cylinder deactivation only RECOMENDS premium fuel.
What are the two exact model years/model names were talking here?
Originally Posted By: OVERKILL
Originally Posted By: shDK
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
I am not saying that i know for sure that is the reason. But as far as i remember, US 87 regular equals Ron 91, and US 91 equals Ron 94. We start at Ron 92 and most cars for the last 10 years require RON95. My car a renault recommends Ron 98. So i use 99.
I know that if you take mazda sky active engines. The ones sold at the US market has a lower compression rate. Then the ones sold on the European markets. The reason should be differences in petrol.
Originally Posted By: shDK
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
I am not saying that i know for sure that is the reason. But as far as i remember, US 87 regular equals Ron 91, and US 91 equals Ron 94. We start at Ron 92 and most cars for the last 10 years require RON95. My car a renault recommends Ron 98. So i use 99.
I know that if you take mazda sky active engines. The ones sold at the US market has a lower compression rate. Then the ones sold on the European markets. The reason should be differences in petrol.
Acura V-6s seem to create vibrations that some owners find objectionable when cylinders are deactivated. There was also a class-action lawsuit against Honda for excessive oil consumption on this engine a few years ago.
I was shopping in the same size class and excluded the RDX because of the premium fuel requirement and the vibration and oil consumption issues. Honda says the oil consumption problem has been fixed, but...
I was shopping in the same size class and excluded the RDX because of the premium fuel requirement and the vibration and oil consumption issues. Honda says the oil consumption problem has been fixed, but...
It seems to have been so far in my folks' 2014 MDX. You simply cannot discern the mode of the engine (number of cylinders) from the driver's seat, and there is no "eco" light or anything to tell you that some have turned off. They have well over 20k miles on their MDX now and there hasn't been any measurable oil consumption.
I'm on dad hard to keep the oil changed every 5k miles on it. With the 0W-20 requirement (pretty much synthetic only), I'm sure it's fine for longer, but I don't trust Honda's Maintenance Minder on VCM engines.
I'm on dad hard to keep the oil changed every 5k miles on it. With the 0W-20 requirement (pretty much synthetic only), I'm sure it's fine for longer, but I don't trust Honda's Maintenance Minder on VCM engines.
If an extra few cents a gallon is enough to think about than maybe a $40k SUV is a bit much...
Originally Posted By: Eddie
(Snip) ...
The down side was the engine now Requires premium fuel. So my fuel purchases go up ~ 17.5% and I gain ~ one MPG on the highway but, no increase for city or combined. So they have a much more complicated valve timing cylinder head and a fuel requirement that goes from 87 to 91 octane. What were the engineers thinking when they did this foolish trade-off? Ed
They were thinking "we earned our bonuses this year".
It's a mistake to assume those Engineers serve but one Master -- the Consumer. It just so happens when they serve a different Master -- the EPA ... Screwing the consjmer is still a "win" if Fuel Economy *appears* to improve.
I say "appears" because actual Fuel Economy is irrelevant; what matters is how well the Engine Management Software sips fuel while operating on the EPA Test Loop.
Suppose using more Auto Trans gears allows more operation at lower RPM and suppose Premium Fuel reduces knock at part-load low-RPM operation. Do you think they would then require Premium (because if it's not required, it won't be used in the EPA Test Loop)?
(Snip) ...
The down side was the engine now Requires premium fuel. So my fuel purchases go up ~ 17.5% and I gain ~ one MPG on the highway but, no increase for city or combined. So they have a much more complicated valve timing cylinder head and a fuel requirement that goes from 87 to 91 octane. What were the engineers thinking when they did this foolish trade-off? Ed
They were thinking "we earned our bonuses this year".
It's a mistake to assume those Engineers serve but one Master -- the Consumer. It just so happens when they serve a different Master -- the EPA ... Screwing the consjmer is still a "win" if Fuel Economy *appears* to improve.
I say "appears" because actual Fuel Economy is irrelevant; what matters is how well the Engine Management Software sips fuel while operating on the EPA Test Loop.
Suppose using more Auto Trans gears allows more operation at lower RPM and suppose Premium Fuel reduces knock at part-load low-RPM operation. Do you think they would then require Premium (because if it's not required, it won't be used in the EPA Test Loop)?
wemay
Site Donor 2023
2016 RDX
http://www.acura.com/engine.aspx?model=rdx
Specifications
DIMENSIONS/CAPACITIES
ENGINE
DRIVETRAIN
CHASSIS
WARRANTIES
VIEW SPECIFICATIONS FOR ANOTHER VEHICLE:
Engine Type
Aluminum-alloy V-6
Displacement
3.5 liters
Valvetrain
24-valve, SOHC i-VTEC®
Horsepower @ rpm (SAE net)
279 @ 6200
Torque (lb-ft @ rpm) (SAE net)
252 @ 4900
EPA Fuel Economy Ratings27 (city / highway / combined)
20 / 29 / 23: Front-wheel drive
19 / 28 / 22: AWD
Recommended Fuel
Premium unleaded 91 octane
Compression Ratio
10.5:1
Throttle Control
Drive-by-Wire™ throttle system
CARB Emissions Rating
ULEV-2
Tune-Up Interval3
No scheduled tune-ups required for 100,000 +/- miles
EPA MPG Rating (city / hwy / combined)27
RDX20 / 29 / 23
RDX AWD19 / 28 / 22
I can't find where it says requires
http://www.acura.com/engine.aspx?model=rdx
Specifications
DIMENSIONS/CAPACITIES
ENGINE
DRIVETRAIN
CHASSIS
WARRANTIES
VIEW SPECIFICATIONS FOR ANOTHER VEHICLE:
Engine Type
Aluminum-alloy V-6
Displacement
3.5 liters
Valvetrain
24-valve, SOHC i-VTEC®
Horsepower @ rpm (SAE net)
279 @ 6200
Torque (lb-ft @ rpm) (SAE net)
252 @ 4900
EPA Fuel Economy Ratings27 (city / highway / combined)
20 / 29 / 23: Front-wheel drive
19 / 28 / 22: AWD
Recommended Fuel
Premium unleaded 91 octane
Compression Ratio
10.5:1
Throttle Control
Drive-by-Wire™ throttle system
CARB Emissions Rating
ULEV-2
Tune-Up Interval3
No scheduled tune-ups required for 100,000 +/- miles
EPA MPG Rating (city / hwy / combined)27
RDX20 / 29 / 23
RDX AWD19 / 28 / 22
I can't find where it says requires
Last edited:
Would you want to keep a complicated vehicle like this after the factory warranty expires?
wemay
Site Donor 2023
To late to EDIT my previous post. I did see this, if you read the orange number 19 footnote associated with the "RECOMMENDATION"...
Recommended Fuel
Some models require premium fuel and for others, it's recommended. Consult your dealer for details.
Recommended Fuel
Some models require premium fuel and for others, it's recommended. Consult your dealer for details.
Last edited:
It amazes me to a degree how people try to justify running cheaper gas in their cars. If it says "recommended" than I can in reality run regular because it doesn't state "required". If higher octane is recommended it is for a good reason. In reality one could CERTAINLY run 87 in any car period.
My car is specd for premium gas. For a reason. I ran across a lady with a 3.5 brand spanking new Maxima with temporary tags on it. She said the car was running terribly. Why??? Running regular cheap 87 in it. I informed her that her car needed 93. Hopefully by doing this it fixed her problem. If not than her fuel injectors and or spark plugs being replaced would likely be on her dime. Changing her plugs alone north of $500.
Here there is a 50 cents difference between regular and premium. In a 20 gallon tank that's obviously $10 a tank. Let's say one uses 6 tanks a month. For a year that is $720 extra per year for gas. Notable. Yes. But if someone is going to buy a $40,000 vehicle than I would tend to believe an extra $60 a month shouldn't break the bank. If yes than obviously go ahead and purchase another lower cost vehicle that is meant to run on 87 only.
And there is absolutely nothing wrong with doing this as well.
The CAFE standards are really not quite has helpful in a number of ways. Good intent DOES not always consider all eventual real world effects.
My car is specd for premium gas. For a reason. I ran across a lady with a 3.5 brand spanking new Maxima with temporary tags on it. She said the car was running terribly. Why??? Running regular cheap 87 in it. I informed her that her car needed 93. Hopefully by doing this it fixed her problem. If not than her fuel injectors and or spark plugs being replaced would likely be on her dime. Changing her plugs alone north of $500.
Here there is a 50 cents difference between regular and premium. In a 20 gallon tank that's obviously $10 a tank. Let's say one uses 6 tanks a month. For a year that is $720 extra per year for gas. Notable. Yes. But if someone is going to buy a $40,000 vehicle than I would tend to believe an extra $60 a month shouldn't break the bank. If yes than obviously go ahead and purchase another lower cost vehicle that is meant to run on 87 only.
And there is absolutely nothing wrong with doing this as well.
The CAFE standards are really not quite has helpful in a number of ways. Good intent DOES not always consider all eventual real world effects.
Last edited:
OVERKILL
$100 Site Donor 2021
Originally Posted By: shDK
Originally Posted By: OVERKILL
Originally Posted By: shDK
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
I am not saying that i know for sure that is the reason. But as far as i remember, US 87 regular equals Ron 91, and US 91 equals Ron 94. We start at Ron 92 and most cars for the last 10 years require RON95. My car a renault recommends Ron 98. So i use 99.
I know that if you take mazda sky active engines. The ones sold at the US market has a lower compression rate. Then the ones sold on the European markets. The reason should be differences in petrol.
https://en.wikipedia.org/wiki/Octane_rating
87 US/CAN = 91-92 RON (so your regular is the same as ours)
91-92 US/CAN = 95 RON (which is what my BMW requires, we call this "premium" and is at every station in Canada)
93-94 US/CAN = 98-100 RON This is available at most Petro-Canada stations as "Ultra 94" and select others like Pioneer (93). It is not abundant in Canada. However, I see 93/94 frequently when I am in the USA, it is very common.
Originally Posted By: OVERKILL
Originally Posted By: shDK
Perhaps the engine was not only developed for the US market. The need for higher octane petrol might not be a problem on markets with already higher octane basic petrol.
What markets would those be? There are different octane measuring methodologies used between countries so you can't just go by the advertised number on the pump.
I am not saying that i know for sure that is the reason. But as far as i remember, US 87 regular equals Ron 91, and US 91 equals Ron 94. We start at Ron 92 and most cars for the last 10 years require RON95. My car a renault recommends Ron 98. So i use 99.
I know that if you take mazda sky active engines. The ones sold at the US market has a lower compression rate. Then the ones sold on the European markets. The reason should be differences in petrol.
https://en.wikipedia.org/wiki/Octane_rating
87 US/CAN = 91-92 RON (so your regular is the same as ours)
91-92 US/CAN = 95 RON (which is what my BMW requires, we call this "premium" and is at every station in Canada)
93-94 US/CAN = 98-100 RON This is available at most Petro-Canada stations as "Ultra 94" and select others like Pioneer (93). It is not abundant in Canada. However, I see 93/94 frequently when I am in the USA, it is very common.
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