Which type of gas?
09-14-2019, 11:46 AM
#42
Suzuka Master
09-14-2019, 11:49 AM
#44
Skeptic
I've used both 87 and 93 and not noticed a difference. But I generally run 93. Who knows what I'm actually getting? But I had a Subaru about 30 years ago that was very "gas sensitive". Ran like shit on Mobil, Hess, etc. But ran good on Amoco (now BP). So, I've been using the same station ever since. Never had a fuel-related problem in any car.
09-14-2019, 11:54 AM
#45
Suzuka Master
Not every luxury car puts premium as recommended, my wifes es350 lexus recommends 87 or higher, there could be a reason why Honda made it recommended for rdx. We can speculate all we want, but we dont know why.
09-14-2019, 06:01 PM
#46
Is anyone out there splitting the difference and going with the 89 octane mid-grade? It seems the biggest cost jump is when going from 87 to 89, and then a small cost increase from 89 to 91 or 93. That's what I was thinking I would do, but then as NooYawkuh points out above, at that point its just an extra 10 cents a gallon to get the premium.
09-14-2019, 07:52 PM
#47
Skeptic
Is anyone out there splitting the difference and going with the 89 octane mid-grade? It seems the biggest cost jump is when going from 87 to 89, and then a small cost increase from 89 to 91 or 93. That's what I was thinking I would do, but then as NooYawkuh points out above, at that point its just an extra 10 cents a gallon to get the premium.
09-15-2019, 11:54 AM
#50
Senior Moderator
Go with what the owner's manual says. If you wanna play, you gotta pay.
09-15-2019, 03:12 PM
#51
Gearhead
There is playing and there is just throwing your money away. So many people buy into FUD. FUD is fear, uncertainty and doubt. Recommended does NOT mean required!
Rather than speculating on whether it needs it or not, I hooked up my data logger and checked my timing for 87, 91 and a blend of 87&91 for about 89 octane. Normally you would see the ECU start to pull timing if it was having issues such as detonation. I tried a wide variety of loads, gears and all in hot temps (which would make detonation (knocking)) more likely. I also ran some timed performance runs.
I won't see there might not be a difference but you might only see it on a dyno. I can't find any difference in peak acceleration, timing retardation or anything else I could measure. If you are running your Acura in a stock state of tune, my results show you would just be flushing your money down the fuel tank if you are running anything over 87 octane. I run top tier fuel regardless of octane and will stick with that.
Of course it is your money and you feel like you somehow get better performance, then great. Good for you, spend the extra $$$ on premium. In my car it made no difference. I have probably ran a good 50 0-60 runs and the biggest factor is launch technique rather than fuel.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
It is your money of course
Rather than speculating on whether it needs it or not, I hooked up my data logger and checked my timing for 87, 91 and a blend of 87&91 for about 89 octane. Normally you would see the ECU start to pull timing if it was having issues such as detonation. I tried a wide variety of loads, gears and all in hot temps (which would make detonation (knocking)) more likely. I also ran some timed performance runs.
I won't see there might not be a difference but you might only see it on a dyno. I can't find any difference in peak acceleration, timing retardation or anything else I could measure. If you are running your Acura in a stock state of tune, my results show you would just be flushing your money down the fuel tank if you are running anything over 87 octane. I run top tier fuel regardless of octane and will stick with that.
Of course it is your money and you feel like you somehow get better performance, then great. Good for you, spend the extra $$$ on premium. In my car it made no difference. I have probably ran a good 50 0-60 runs and the biggest factor is launch technique rather than fuel.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
It is your money of course
09-15-2019, 03:22 PM
#52
In my car it made no difference. I have probably ran a good 50 0-60 runs and the biggest factor is launch technique rather than fuel.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
09-15-2019, 03:23 PM
#53
Senior Moderator
There is playing and there is just throwing your money away. So many people buy into FUD. FUD is fear, uncertainty and doubt. Recommended does NOT mean required!
Rather than speculating on whether it needs it or not, I hooked up my data logger and checked my timing for 87, 91 and a blend of 87&91 for about 89 octane. Normally you would see the ECU start to pull timing if it was having issues such as detonation. I tried a wide variety of loads, gears and all in hot temps (which would make detonation (knocking)) more likely. I also ran some timed performance runs.
I won't see there might not be a difference but you might only see it on a dyno. I can't find any difference in peak acceleration, timing retardation or anything else I could measure. If you are running your Acura in a stock state of tune, my results show you would just be flushing your money down the fuel tank if you are running anything over 87 octane. I run top tier fuel regardless of octane and will stick with that.
Of course it is your money and you feel like you somehow get better performance, then great. Good for you, spend the extra $$$ on premium. In my car it made no difference. I have probably ran a good 50 0-60 runs and the biggest factor is launch technique rather than fuel.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
It is your money of course
Rather than speculating on whether it needs it or not, I hooked up my data logger and checked my timing for 87, 91 and a blend of 87&91 for about 89 octane. Normally you would see the ECU start to pull timing if it was having issues such as detonation. I tried a wide variety of loads, gears and all in hot temps (which would make detonation (knocking)) more likely. I also ran some timed performance runs.
I won't see there might not be a difference but you might only see it on a dyno. I can't find any difference in peak acceleration, timing retardation or anything else I could measure. If you are running your Acura in a stock state of tune, my results show you would just be flushing your money down the fuel tank if you are running anything over 87 octane. I run top tier fuel regardless of octane and will stick with that.
Of course it is your money and you feel like you somehow get better performance, then great. Good for you, spend the extra $$$ on premium. In my car it made no difference. I have probably ran a good 50 0-60 runs and the biggest factor is launch technique rather than fuel.
Now if I were running a tune I would definitely go for whatever the tuner recommended as they likely tuned it to truly take advantage of the higher octane with more boost and timing advance.
It is your money of course
If it is recommended, then yeah, per your post, it's all good. The average driver will not see much of a difference albeit maybe a slight reduction in acceleration power and fuel efficiency...
09-15-2019, 05:55 PM
#55
Senior Moderator
09-15-2019, 05:59 PM
#56
Suzuka Master
Um, yes they do: http://m.acura.com/pdf/owners/2019/R...ss_Fueling.pdf
I read it, all it says it this: "Use of unleaded gasoline of 91 octane or higher is recommended". There is no explanation why 91 or higher is recommended
Last edited by russianDude; 09-15-2019 at 06:09 PM.
09-15-2019, 06:54 PM
#58
Suzuka Master
09-15-2019, 07:01 PM
#59
Gearhead
If there is any reduction in acceleration of fuel efficiency, I can't quantify it. If I saw it pulling timing somewhere I might believe. If we compare it to the Accord 2.0T (runs on regular) the RDX makes about 20HP but only a bit more TQ 7 lb/ft but at 100 rpm higher than the Accord. What is interesting is both make peak power (according to Hondacura) at 6500 rpm.
My RDX has never ever hit 6500 rpm in any gear while accelerating. During testing today, at WOT in S+ and S (trans) it upshifted into 2nd at 6000.
As for why Hondacura put recommended in the manual, likely because most "premium" cars require premium. An even better way to settle it is to look at what the Civic Type R takes for fuel. It is running 23.2 psi for boost (far higher than I've ever seen). It has 306 HP @ 6500 rpm and 295 lb/ft torque from 2500-4500. So what does Hondacura say for that motor? Required fuel: Regular Unleaded (Premium Recommended).
So if that motor, which is definitely more highly stressed than ours is fine for regular fuel, you are likely just pouring your $$$ down the drain whenever you fill up with premium. If it is running 23.2 psi boost on regular I am sure ours will have no issue at a more lowly 15-19 psi. Again its your dollars but I am going to save mine. I'll revisit if/when I tow something and see if the heavier load brings out a need for it.
My RDX has never ever hit 6500 rpm in any gear while accelerating. During testing today, at WOT in S+ and S (trans) it upshifted into 2nd at 6000.
As for why Hondacura put recommended in the manual, likely because most "premium" cars require premium. An even better way to settle it is to look at what the Civic Type R takes for fuel. It is running 23.2 psi for boost (far higher than I've ever seen). It has 306 HP @ 6500 rpm and 295 lb/ft torque from 2500-4500. So what does Hondacura say for that motor? Required fuel: Regular Unleaded (Premium Recommended).
So if that motor, which is definitely more highly stressed than ours is fine for regular fuel, you are likely just pouring your $$$ down the drain whenever you fill up with premium. If it is running 23.2 psi boost on regular I am sure ours will have no issue at a more lowly 15-19 psi. Again its your dollars but I am going to save mine. I'll revisit if/when I tow something and see if the heavier load brings out a need for it.
09-15-2019, 07:22 PM
#60
Safety Car
AFAIK, the only Acura vehicle that actually requires premium is the NSX (duh).
AAA used science to address this exact question What do I do if my car only recommends premium, but does not require it?: https://www.autoclubmo.aaa.com/automotive/advocacy/premium-fuel-study-phase2.html
Basically the results show that if your car merely "recommends" premium, in vast majority of situations that they tested, the additional price % hike of premium is not worth the increase in performance/mpg, if any.
I would love to see a replicate study done with lot more vehicles
09-15-2019, 08:46 PM
#62
Drifting
Join Date: Apr 2018
Location: New Yorkie, Hudson Valley
Posts: 3,001
Received 1,026 Likes
on
716 Posts
Even if the results are minor, 4 or 5 horses, 1 mpg someplace, if they got those numbers on 91, I think they would say 91 is recommended.
I have no hard evidence to back this up, but this is the internet, is it not?
I have no hard evidence to back this up, but this is the internet, is it not?
09-15-2019, 09:24 PM
#63
Gearhead
Well, I like hard evidence. So that is why I setup data logging on mine and did a few comparisons. My suspicions have been further bolstered. I have finally found the factory specs for the boost on the RDX.
The factory specs call for max boost of 20.5 psi. The Civic Type R is running 23.2 (and takes regular). They are both running the same compression ratio (as is the Accord). So if any car in the Hondacura 2.0 liter turbo motor lineup needed premium it should have been the Type (running more boost) and Honda doesn't require it.
So feel free to pour in anything over 87 octane in your fuel tank if it makes you feel better. If the much more highly tuned Civic Type R can run on something other than premium I am pretty certain our less powerful motors should be fine. I can't find anything else in the spec sheets that would point to a need if the Type R doesn't need it.
The factory specs call for max boost of 20.5 psi. The Civic Type R is running 23.2 (and takes regular). They are both running the same compression ratio (as is the Accord). So if any car in the Hondacura 2.0 liter turbo motor lineup needed premium it should have been the Type (running more boost) and Honda doesn't require it.
So feel free to pour in anything over 87 octane in your fuel tank if it makes you feel better. If the much more highly tuned Civic Type R can run on something other than premium I am pretty certain our less powerful motors should be fine. I can't find anything else in the spec sheets that would point to a need if the Type R doesn't need it.
09-15-2019, 09:39 PM
#64
Safety Car
So looks like further data supports the general notion that premium is not worth the increased cost proportional to its miniscule to non-existent real world increase in performance/mpg. CLearly outliwers exist in the C/D test with the F150 and in the AAA test with their Audi I believe. Why did C/D use the M5 to test 91 vs 93 is beyond me...cars like the M5 clearly require premium anyway
Last edited by nist7; 09-15-2019 at 09:41 PM.
09-23-2019, 06:12 PM
#65
User Awaiting Email Confirmation
I fill up with 93. My reasoning is this bullshit DI crudding up the intake valves. I'm hoping that this prevents or at least delays the amount of carbon build up on the intake valves that plagues DI engines. Also going to run some CRC intake cleaner thru a vacuum hose every few oil changes.
09-23-2019, 06:41 PM
#66
I fill up with 93. My reasoning is this bullshit DI crudding up the intake valves. I'm hoping that this prevents or at least delays the amount of carbon build up on the intake valves that plagues DI engines. Also going to run some CRC intake cleaner thru a vacuum hose every few oil changes.
That’s of course assuming our RDX’s will even have this issue.
09-24-2019, 12:43 AM
#67
User Awaiting Email Confirmation
I was very active in the Audi forums as I had an 08 A6 3.2. There were many users that still had the carbon buildup on the intake valves and they only used premium 91 or 93 (RS4 drivers also chimed in). Thus I don’t think it will help at all with carbon buildup based on my several years following that issue on the Audi forums.
That’s of course assuming our RDX’s will even have this issue.
That’s of course assuming our RDX’s will even have this issue.
The following users liked this post:
Midnight Mystery (09-24-2019)
09-24-2019, 05:55 PM
#68
Suzuka Master
I dont see how Honda recommendation for premium should be completely dismissed based on some articles that studied usage of premium gas in cars without premium being mentioned in owner manual. Just a lot of speculation to support someones choice of gas.
09-24-2019, 07:37 PM
#69
09-24-2019, 08:11 PM
#70
Gearhead
Higher octane fuel resists detonation/pre-ignition (knocking) better. That is it. So if you aren't having issues with knocking/detonation/pre-ignition any extra octane is just a waste.
Normally if the car starts to encounter knock the knock sensor will talk with the ECU and make changes. What changes might they be? Typically reducing ignition timing and boost.
When I am more likely to encounter detonation when driving? Heavy loads and hot days are probably the 2 most likely. With turbo cars a lot of boost makes the engine more prone to know and/or a lean air fuel mixture. So let's suppose you are in Florida, 100 degree day, car is fully loaded and you mash on the throttle while in 10th gear and going up a hill. That is probably the most likely scenario to encounter detonation/knock/pre-ignition. As soon as your RDX starts to downshift the load is actually a bit easier on the motor as the transmission is helping out more with torque multiplication.
Well I ran my RDX as near as I could to the above scenario while logging for ignition timing and watching the know sensor. I also did runs full throttle. I did it with both regular and premium. My car never pulled (reduced) ignition timing. I couldn't see any meaningful difference in the knock sensor. So for my car, in hot Florida, AC on, and fully loaded premium doesn't help me a bit. Best thing I can do is run top tier fuel rather than dump the premium out my exhaust. Normally if I timing was reduced, there might be an impact in fuel economy. I see no difference there nor does my RDX run any slower when on 87.
Now if I were running a tune, Ktuner or Hondata, and they were tweaking timing and boost, most likely I would need to run premium to get the best performance and reliability. If you are just going down the road ast 70 mph at a steady state, your engine doesn't likely care if you were running even 85 octane. Matter of fact, at high altitudes you aren't likely to find 91 anyway.
With the modern ECU with good knock sensors, your RDX will keep you out of trouble in the really rare chance your RDX actually needs premium even though mine doesn't. Go buy an OBD adapter and get a program and see for yourself. The difference in running 87 vs 91 will pay for the adapter and program in just a few tanks.
Again it is your car and money and if you think somehow you are getting a benefit, then run premium.
Normally if the car starts to encounter knock the knock sensor will talk with the ECU and make changes. What changes might they be? Typically reducing ignition timing and boost.
When I am more likely to encounter detonation when driving? Heavy loads and hot days are probably the 2 most likely. With turbo cars a lot of boost makes the engine more prone to know and/or a lean air fuel mixture. So let's suppose you are in Florida, 100 degree day, car is fully loaded and you mash on the throttle while in 10th gear and going up a hill. That is probably the most likely scenario to encounter detonation/knock/pre-ignition. As soon as your RDX starts to downshift the load is actually a bit easier on the motor as the transmission is helping out more with torque multiplication.
Well I ran my RDX as near as I could to the above scenario while logging for ignition timing and watching the know sensor. I also did runs full throttle. I did it with both regular and premium. My car never pulled (reduced) ignition timing. I couldn't see any meaningful difference in the knock sensor. So for my car, in hot Florida, AC on, and fully loaded premium doesn't help me a bit. Best thing I can do is run top tier fuel rather than dump the premium out my exhaust. Normally if I timing was reduced, there might be an impact in fuel economy. I see no difference there nor does my RDX run any slower when on 87.
Now if I were running a tune, Ktuner or Hondata, and they were tweaking timing and boost, most likely I would need to run premium to get the best performance and reliability. If you are just going down the road ast 70 mph at a steady state, your engine doesn't likely care if you were running even 85 octane. Matter of fact, at high altitudes you aren't likely to find 91 anyway.
With the modern ECU with good knock sensors, your RDX will keep you out of trouble in the really rare chance your RDX actually needs premium even though mine doesn't. Go buy an OBD adapter and get a program and see for yourself. The difference in running 87 vs 91 will pay for the adapter and program in just a few tanks.
Again it is your car and money and if you think somehow you are getting a benefit, then run premium.
09-24-2019, 08:53 PM
#71
User Awaiting Email Confirmation
Higher octane fuel resists detonation/pre-ignition (knocking) better. That is it. So if you aren't having issues with knocking/detonation/pre-ignition any extra octane is just a waste.
Normally if the car starts to encounter knock the knock sensor will talk with the ECU and make changes. What changes might they be? Typically reducing ignition timing and boost.
When I am more likely to encounter detonation when driving? Heavy loads and hot days are probably the 2 most likely. With turbo cars a lot of boost makes the engine more prone to know and/or a lean air fuel mixture. So let's suppose you are in Florida, 100 degree day, car is fully loaded and you mash on the throttle while in 10th gear and going up a hill. That is probably the most likely scenario to encounter detonation/knock/pre-ignition. As soon as your RDX starts to downshift the load is actually a bit easier on the motor as the transmission is helping out more with torque multiplication.
Well I ran my RDX as near as I could to the above scenario while logging for ignition timing and watching the know sensor. I also did runs full throttle. I did it with both regular and premium. My car never pulled (reduced) ignition timing. I couldn't see any meaningful difference in the knock sensor. So for my car, in hot Florida, AC on, and fully loaded premium doesn't help me a bit. Best thing I can do is run top tier fuel rather than dump the premium out my exhaust. Normally if I timing was reduced, there might be an impact in fuel economy. I see no difference there nor does my RDX run any slower when on 87.
Now if I were running a tune, Ktuner or Hondata, and they were tweaking timing and boost, most likely I would need to run premium to get the best performance and reliability. If you are just going down the road ast 70 mph at a steady state, your engine doesn't likely care if you were running even 85 octane. Matter of fact, at high altitudes you aren't likely to find 91 anyway.
With the modern ECU with good knock sensors, your RDX will keep you out of trouble in the really rare chance your RDX actually needs premium even though mine doesn't. Go buy an OBD adapter and get a program and see for yourself. The difference in running 87 vs 91 will pay for the adapter and program in just a few tanks.
Again it is your car and money and if you think somehow you are getting a benefit, then run premium.
Normally if the car starts to encounter knock the knock sensor will talk with the ECU and make changes. What changes might they be? Typically reducing ignition timing and boost.
When I am more likely to encounter detonation when driving? Heavy loads and hot days are probably the 2 most likely. With turbo cars a lot of boost makes the engine more prone to know and/or a lean air fuel mixture. So let's suppose you are in Florida, 100 degree day, car is fully loaded and you mash on the throttle while in 10th gear and going up a hill. That is probably the most likely scenario to encounter detonation/knock/pre-ignition. As soon as your RDX starts to downshift the load is actually a bit easier on the motor as the transmission is helping out more with torque multiplication.
Well I ran my RDX as near as I could to the above scenario while logging for ignition timing and watching the know sensor. I also did runs full throttle. I did it with both regular and premium. My car never pulled (reduced) ignition timing. I couldn't see any meaningful difference in the knock sensor. So for my car, in hot Florida, AC on, and fully loaded premium doesn't help me a bit. Best thing I can do is run top tier fuel rather than dump the premium out my exhaust. Normally if I timing was reduced, there might be an impact in fuel economy. I see no difference there nor does my RDX run any slower when on 87.
Now if I were running a tune, Ktuner or Hondata, and they were tweaking timing and boost, most likely I would need to run premium to get the best performance and reliability. If you are just going down the road ast 70 mph at a steady state, your engine doesn't likely care if you were running even 85 octane. Matter of fact, at high altitudes you aren't likely to find 91 anyway.
With the modern ECU with good knock sensors, your RDX will keep you out of trouble in the really rare chance your RDX actually needs premium even though mine doesn't. Go buy an OBD adapter and get a program and see for yourself. The difference in running 87 vs 91 will pay for the adapter and program in just a few tanks.
Again it is your car and money and if you think somehow you are getting a benefit, then run premium.
09-25-2019, 10:18 AM
#72
"Cleaner Engine?
Some drivers are under the impression that premium fuels leave less carbon deposits in engines because they have better detergency. In actuality, one doesn't really have anything to do with the other. There are some fuels that are called 'top tier' fuels because they have extra detergency in them to a certain level that is certified by the makes of the fuel to be superior. But this doesn't relate to their octane level. You can have a regular gasoline with top-tier detergency and you can have a premium gas with the same."So in short, both premium and 87 'top tier' fuels have the same level of detergent, only different is the octane level..to claim can cause more or quick carbon buildup on lower octane is inaccurate, don't take my word for it, just google..
09-25-2019, 02:54 PM
#73
Gearhead
For logging I've used OBD Fusion for IOS and Torque Pro on Android. None of my Torque Pro logs are saved as they were on a phone that was replaced. I'll look and see if I have anything left from my OBD Fusion logs. The problem with that program is earlier on it wasn't logging frequently enough so I started using Torque Pro again. I also did some runs with a Ktuner that a friend has. It has good monitoring capability but I didn't have any logging turned own. It has a pretty handy way of monitoring the knock sensor. Would have been cool to try a tune but no tune apparently for the 2020 RDX yet so I just used the monitoring capability.
All I can say is with over 50 runs now of 0-60 mph and 20 1/4 mile runs, my absolute best time was when running 87 Octane from Costco. Worst run was on 93 from Costco. Average of both shows almost the same performance. Didn't seem to matter if in Comfort, Sport or Sport + for the times. Comfort with trans in S mode pretty much identical to the Sport + mode but with softer suspension on my Advance. Whether trans was in S or D, or any of the above dynamic modes I couldn't see any real statistical difference in times. Biggest variable was density altitude (temp) for me. So if 93 was giving me better performance, I never saw it anywhere. Even in the few times I ran it from 60-100 where a HP advantage might have shown up and where I was able to pretty much pull peak boost for longer.
All I can say is with over 50 runs now of 0-60 mph and 20 1/4 mile runs, my absolute best time was when running 87 Octane from Costco. Worst run was on 93 from Costco. Average of both shows almost the same performance. Didn't seem to matter if in Comfort, Sport or Sport + for the times. Comfort with trans in S mode pretty much identical to the Sport + mode but with softer suspension on my Advance. Whether trans was in S or D, or any of the above dynamic modes I couldn't see any real statistical difference in times. Biggest variable was density altitude (temp) for me. So if 93 was giving me better performance, I never saw it anywhere. Even in the few times I ran it from 60-100 where a HP advantage might have shown up and where I was able to pretty much pull peak boost for longer.
09-25-2019, 04:45 PM
#74
User Awaiting Email Confirmation
"Cleaner Engine?
Some drivers are under the impression that premium fuels leave less carbon deposits in engines because they have better detergency. In actuality, one doesn't really have anything to do with the other. There are some fuels that are called 'top tier' fuels because they have extra detergency in them to a certain level that is certified by the makes of the fuel to be superior. But this doesn't relate to their octane level. You can have a regular gasoline with top-tier detergency and you can have a premium gas with the same."So in short, both premium and 87 'top tier' fuels have the same level of detergent, only different is the octane level..to claim can cause more or quick carbon buildup on lower octane is inaccurate, don't take my word for it, just google..
That being said, the reason I prefer to run higher octane is for the reason that lower octane generally leads to retarding of timing by factory ECUs for engines that "recommend" a higher octane. This is what may lead to more carbon build-up from not-so-complete combustion ... of course, it's dependent on how much timing is pulled as to whether it will even make a significant difference in carbon build-up on the intake valves (if at all even). Also, seeing as the fuel never actually touches the intake valves, it wouldn't matter what amount of detergents were in the fuel, or even the brand of fuel used. The fuel itself won't be cleaning the intake valve that plagues DI engines in the first place.
Thread
Thread Starter
Forum
Replies
Last Post
Sounds
3G RDX (2019+)
239
06-04-2021 01:30 PM
mav238
1G RDX (2007-2012)
14
10-13-2009 04:58 PM