When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I tend to side with the people who actually design and test the engines. Acura gets no benefit out of recommending the higher octane. Just like when they recommend a certain weight of oil. Will other weights work? Yes, it will probably be fine but they've determined that a certain weight works best and I'll go with the people who have actually done tests on these engines.
Oh now you've done it, you're gonna get chickdr all riled up again.
Actually i am now just going to be using regular since I have not noticed any unusual engine noise or behaviour while running regular , like I did when I ran regular in my old Murano. In stop and go traffic it would knock a bit and generally it did not seem as though the timing retard system worked as well as it seems to on the RDX.
Most manufacturers design their cars so they can run safely on regular gas, because many owners feel it is a waste of money to run higher octane.
When the mfr recommends a specific octane number, then generally that is where the engine runs most efficiently. Efficiency is not only peak power, but also mpg.
Just wasted a measurable percentage of my life reading this thread. The misconceptions and logic evinced by some are mind boggling. I did some research and did find out that Costco Kirkland Signature gasoline is Top Tier. So, the post somewhere above that stated that the poster's Acura dealer said Costco gasoline wasn't suitable for an Acura might be a little off track. I also found an interesting AAA article with actual test results on the regular vs premium argument. The abbreviated report follows. For the full report click on the link:
ORLANDO, Fla. (Dec. 12, 2017) – According to new research from AAA, premium gasoline offers some benefit to select vehicles, but is becoming increasingly expensive for drivers. In recent years, the price gap between premium and regular-grade gasoline has risen from a historically steady 10 percent to 25 percent or more per gallon. While past AAA research has shown no benefit in using premium gasoline in a vehicle designed to operate on regular fuel, new testing indicates that some vehicles – those that recommend, but do not require premium gasoline – may see increased fuel economy and performance under certain driving conditions when using the higher-octane gasoline. Unfortunately, the high cost of premium gasoline may outweigh that advantage for many drivers. As a result, AAA recommends drivers weigh the potential benefits against the cost of using premium gasoline, if their vehicle does not require it.
“AAA’s testing reveals that drivers could see modest gains in fuel economy and performance when opting for premium gasoline in vehicles that recommend, but do not require, the higher-octane fuel,” said Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center. “Those seeking the maximum capabilities of their performance-focused or utility vehicle may see some benefit from using premium gasoline, particularly over the long haul.”In partnership with the Automobile Club of Southern California’s Automotive Research Center, AAA tested a variety of vehicles that recommend, but do not require, the use of premium (91 octane or higher) gasoline. Although drivers of these vehicles are unlikely to see any benefit from using premium gasoline during typical city or highway driving, a combination of laboratory and on-road tests were performed to simulate extreme driving scenarios such as towing, hauling cargo and aggressive acceleration. When using premium fuel in these vehicles under these conditions, AAA tests found that:
Fuel economy for test vehicles averaged a 2.7 percent improvement. Individual vehicle test result averages ranged from a decrease of 1 percent (2016 Audi A3) to an improvement of 7.1 percent (2016 Cadillac Escalade).
Horsepower for test vehicles averaged an increase of 1.4 percent. Individual vehicle test result averages ranged from a decrease of 0.3 percent (2016 Jeep Renegade) to an improvement of 3.2 percent (2017 Ford Mustang).
According to national averages, the price difference between regular and premium gasoline is approximately 20 to 25 percent, or 50 cents per gallon.
The modest fuel economy improvements found in AAA tests do not offset the higher cost of premium gasoline.
“There’s no question that higher-octane premium fuel has the potential to boost a vehicle’s fuel economy and performance, however, engines have to be calibrated to require that fuel to see the full benefit,” said John Nielsen, AAA’s managing director of Automotive Engineering and Repair. “Based on AAA’s testing, vehicles that only recommend premium gasoline can’t take full advantage of higher octane fuel and, as a result, the benefit that comes from upgrading to premium gasoline may not offset its high cost.”Last year, nearly 1.5 million new vehicles sold in the United States recommend, but do not require, premium gasoline. The trend toward recommending or requiring higher-octane fuel continues to rise as manufacturers work toward meeting stringent CAFE (Corporate Average Fuel Economy) standards. However, a vehicle that requires the more expensive premium gasoline may dissuade a car buyer, leaving automakers to balance higher performance with what consumers desire. Rising prices for premium gasoline, coupled with great variation in prices across the country, compounds this issue. AAA urges drivers who use premium gasoline to shop around for the best price, as it could vary dramatically between gas stations in any given city. The AAA Mobile app, available for iPhone, iPad and Android, can help drivers identify the least expensive premium gasoline near them.“The gap between premium and regular gas has been steadily rising since 2009, with the most dramatic increase occurring in the last two years,” said Jeanette Casselano, AAA gas price expert. “Fewer than five years ago, only a 10 percent gap existed between premium and regular. Today, that spread has doubled with premium gasoline costing almost 50 cents more per gallon and is still climbing despite the fact that consumer demand for premium isn’t necessarily increasing. ”For those vehicles that do not recommend or require premium gasoline, AAA suggests drivers opt for the lower priced, regular fuel. In a study released last year, AAA found that consumers wasted nearly $2.1 billion dollars fueling these vehicles with higher-octane gasoline. However, drivers of vehicles that require premium gasoline should always use it. Additionally, any vehicle that makes a “pinging” or “knocking” sound while using regular gasoline should be evaluated by a repair facility and likely switched to a higher-octane fuel. Drivers seeking a higher quality fuel for their vehicle should consider using one that meets Top Tier standards, as previous AAA research found it to keep engines up to 19 times cleaner.The full report, fact sheet and other information regarding this study can be found on the AAA NewsRoom.
Last edited by mgrody; Jun 21, 2018 at 09:06 PM.
Reason: Add link to full report
Again, discussed ad nauseum. Those that have chosen to use Regular, use Regular. Same goes for those using Premium. One thing I can tell you is as we get closer to truly global car standards, higher grade fuels will be mandated more in higher efficiency engines. RL uses the 3.5/3.7 liter V6 used across multiple platforms, but achieves its marginal increases in power by consuming Premium fuel.
Again, discussed ad nauseum. Those that have chosen to use Regular, use Regular. Same goes for those using Premium. One thing I can tell you is as we get closer to truly global car standards, higher grade fuels will be mandated more in higher efficiency engines. RL uses the 3.5/3.7 liter V6 used across multiple platforms, but achieves its marginal increases in power by consuming Premium fuel.
Okay, feel free to ignore. All I've read on this thread are personal opinions. So, I thought actual test results might be in order.
Okay, feel free to ignore. All I've read on this thread are personal opinions. So, I thought actual test results might be in order.
Don't get me wrong, I appreciate your comments and efforts to share what you've learned. Sadly, there are those whom you will never be able to appease and will continue doing what they want...hence, Regular to Regular and Premium to Premium.
Would someone please provide the exact engine number/numbers used in the 2017 and 2018 RDX's sold here in the US?
I thought I'd ask in this thread being it could be relevant information to make an informed decision on required octane.
Also, which if any of the Honda products share this/these identical engine/engines?
Would someone please provide the exact engine number/numbers used in the 2017 and 2018 RDX's sold here in the US?
I thought I'd ask in this thread being it could be relevant information to make an informed decision on required octane.
Also, which if any of the Honda products share this/these identical engine/engines?
Thank You,
John
Post #320 above....for the 2017 model of RDX and Accord.
^ I compared both the 2017 RDX and 2017 Honda V6 with Auto shortly after buying my RDX almost 2 years ago.
The RDX engine is a J35Z2. I do not know what the engine designation is in the Accord. All I know is they have the same displacement, bore and stroke and compression ratio.
2017 Honda Accord with Auto:
I am not going to worry about it. I used to run high test 91 but now run mid-grade 89. I get the same great gas mileage on the highway 31-36 MPG. My neighbor's 2003 TL-S has run on nothing but regular all its life and it calls for high test.
The best part is, at the 3' 35" mark the guy in the test center has no clue what he is talking about. 30 MPH takes the same HP no matter what fuel you are running. LOL
Okay, thanks for clarifying the above. The last time I studied this subject was for my daughter's 2015 RDX. At the time and after reading all of these post up to that date, I did learn the the exact RDX 3.5 engine number was in fact the same as some Accords. I tell her to run a Top Tier 89 octane to be on the safe side. However, the exact same Accord does state "Regular"
I'm now trying to determine if the same holds true to the 2017 or 2018.
I'm now trying to determine if the same holds true to the 2017 or 2018.
I never bothered to check the Honda Odyssey which has the same engine at the time.
As for 2018, the Honda Accord no longer comes with a V6. But the 2018 Honda Odyssey does and it has the same engine bore and stroke as well as compression ratio (HP and torque slightly different) as my 2017 RDX and guess what, the Odyssey runs on Regular. And I thought the Premium on the RDX was due to the RDX pushing a cube through the air (loading the engine more at speed). Well the Odyssey at speed would be like our RDX...un-aerodynamic.
The best part is, at the 3' 35" mark the guy in the test center has no clue what he is talking about. 30 MPH takes the same HP no matter what fuel you are running. LOL
I never bothered to check the Honda Odyssey which has the same engine at the time.
As for 2018, the Honda Accord no longer comes with a V6. But the 2018 Honda Odyssey does and it has the same engine bore and stroke as well as compression ratio (HP and torque slightly different) as my 2017 RDX and guess what, the Odyssey runs on Regular. And I thought the Premium on the RDX was due to the RDX pushing a cube through the air (loading the engine more at speed). Well the Odyssey at speed would be like our RDX...un-aerodynamic.
These numbers are a little different than what is stated as for horse power and torque..
I'm seeing 279 HP @ 6,200 RPM & 252 FT/LB Torque @ 4,900 RPM..
Look up the J35Y6 VCM engine; that should answer your questions.
Okay, I see where the same engine... ..is my best guess; ..set with a different fuel shot duration and timing advance in order to vary the HP & Torque to better suite the application.
That said, it is possible that a higher octane would prove beneficial if the timing were to be advanced high enough along with corresponding fuel shot duration.
This is just a possibility... ..I'm not stating the 2017 or 2018 RDX is tuned in such a manner to where a higher octane would be beneficial. This is what I'm trying to find out.
The 2013-2015 RDX is spec'd @ 273 HP @ 6,200 RPM verses 2016-2018 RDX 279 HP @ 6,200 RPM
The 2013-2015 RDX is spec'd @ 251 FT/LB @ 5,000 RPM vs 2016-2018 RDX 252 FT/LB @ 4,900 RPM
Would the newer model with 6 more horsepower and a little different torque spec be enough to where a higher octane would be necessary to achieve these numbers..??