colt427

I just bought a new V6 Accord.
Same engine as the RDX.
Yet the recommended gas is regular.

I'll continue to use premium is the RDX.
Though because it's a lease,I go with off brand premium which is around .20-.25 higher than brand name regular.Here brand name premium is usually .80-.90 more than regular.

OriginalLucy

I was going to ask the same question. I have the '14 RDX and was wondering how important it is to always use premium. Can I occasionally fill with mid grade?

thoiboi

eh, it's a lease, do whatever you want to it.

colt427

The Accord is a buy.
The RDX is a lease.
If using premium gains a few more ponies and optimum performance,I'd go Shell 93.That's a 6K- 7K per vehicle so the extra cost is minimal.

justnspace

iTrader: (1)

Octane rating measures how resistant the fuel is to pre-ignition (self-igniting during compression) and detonation (exploding when hit with a spark). An "octane rating" of 100, means that the fuel has the same resistance to ignition as pure "2,2,4 trimethylpentane". An "octane rating" of 0 means that the fuel has the same properties as pure "n-heptane". An "octane rating" of 90, means that the fuel burns similarly to a 90:10 mixture of 2,2,4 TMP and n-heptane. It is possible to have ratings higher than 100, for fuels that are even more difficult to ignite than the reference "octane".

Gasoline engines are designed to take fuel of a specific octane rating. The amount and speed with which an engine compresses a fuel-air mixture is fixed in the design, and nothing can change that. This means that if you have an engine which uses very strong compression (e.g. a highly tuned sports car engine), and put low octane fuel into it, the fuel may "detonate" during compression - causing the engine to "knock" or "ping/pink". The knocking noise is the sound of the fuel exploding - as the engine is not designed to take that pressure, it will suffer severe damage.

Modern cars use electronic ignition and timing control. The car has a microphone bolted to the engine which listens for the sound of the burn. The engine computer analyses that signal and uses it to adjust the ignition timing. If it hears detonation starting to occur, then it delays the timing - if everything seems to be going OK, then it'll try advancing the timing. The computer tends to be programmed with limits based upon typical fuel ratings in the country the car was sold in. So, if you put 110 octane race fuel into a corolla, the computer won't super tune the ignition timing, it'll move it up to where the manufacturer expects premium fuel to be, but go no further.If you put low octane fuel in, the computer will try to delay the ignition timing - but that can only do so much - and if the problem is that the fuel is igniting during compression, there is nothing the computer can do, except put on the check engine light and hope that you stop before you blow the engine.

TL;DR
- the Accord is made or designed to use regular fuel, according to the designers and engineers...
- the RDX is made to account for higher octane so that it doesnt ping or knock
- even tho, they both have the same engine architecture...there's obviously something different about them, either in compression or simply software tune

Gadgetjq

Colt,

You never actually asked a question in your op but you probably intended to ask about whether to use premium or regular in your cars. Rather than re-invent that wheel, check out this post. Hundreds of replies, tens of thousands of views and.....ultimately it comes down to 'The RDX manual only 'recommends' premium fuel so you can go with the manufacturers recommendation or fudge if you want.

colt427

Recommended and not Required.

I'll go with regular in the Accord V6 but stay with off brand premium in the RDX.

justnspace

iTrader: (1)

some one over in the 3G TL back in the day, monitored knock....and found that a mixture of 93 and 100 octane to make some where in the middle of 95 and 96 octane completely stopped knock on the 3G TL.
the 3G TL had one of the highest engine compressions available to the mass market and resulted in a nasty ping or engine knock if lower octane was used.

pretty sure if you used a higher octane in the Accord, you'll see a slight performance gain....as again, they are all using the same engine architecture

chickdr

I've gotten into this before and never got a documented rebuttal so I will say again, as I said in the other thread, there is NO difference at all the the Accord and RDX's V6 motors. They in fact come from the same plant in Ohio. They have identical stats other than one extra hp in the case of the RDX (likely due to exhaust differences). I can see no reason whatsoever to shell out extra $$$ for premium in the RDX. I have 28k on mine and have used regular 99% of the time. I noted no difference in performance, or economy when using premium. No pinging either. If its good enough for the Accord V6, its good enough for the RDX.

justnspace

iTrader: (1)

^compression is different, no?
heads are different, no?

also, redline is different...one redlines at 6800 the other redlines at 6900...

even tho, they use the same engine architecture...in this case it's the J-series....
there's clearly a difference in engine compression ratios

which makes a huge difference in the ability to burn fuel

snorf

When we got our '16 RDX we used the "recommended" premium. After reading some of the posts on this site, I tried a tank of regular. I noted no difference. From that point on I have used 87 octane and have noted no difference in miles to empty or performance. I have never heard the engine ping. I don't check the mileage (when it gets low I just fill it), but I always look at the miles to empty and there was no difference between 87 and 93 octane. I do, however, always use a top-tier gas because it has more detergent and IIRC Acura may require top-tier in the RDX. But I don't really worry about that as I have always used top-tier.

chickdr

No - compression is identical at 10.5:1. The only difference in specs is one less hp (278 vs 279) in the Accord V6. Are you sure about the redline being different? Seems unlikely.

chickdr

Also, where did the info about the heads being different come from? I have never heard this before. Again, it seems very unlikely as both motors have the same specs and even cylinder deactivation. Why would Honda make a different head if it has the same exact result as the Accord motor?

VR1

Both have the 6,800 RPM redline, I checked the RDX gauge cluster and it's redline is 6,800 rpm.
Both have the same 10.5:1 compression ratio
Accord has 278 hp @ 6200 rpm, RDX has 279 hp @ 6200 rpm.
Both have 252 lb-ft tq @ 4900 rpm.
I don't think theres any difference at all between the J35Y1 the Accord and RDX have. I have no clue why premium is recommended.

RDX10

I am 99% sure that they are the same EXACT engine. Acura asks for premium so that you feel like you are driving a luxury car. Lexus used to do this ALL the time.

Skidoor

I use premium even though I really have to watch my expenses. I find it very hard to believe that car manufacturers would bother with psychological tomfoolery like trying to make you feel like you're in a luxury vehicle by recommending premium. They would get much better payback by selling a car that is happy with 87... Also, I filled up with regular 87 a couple times and in both cases I found the engine less responsive on small throttle increases .... especially at higher speeds...and the engine made more noise.

RDX10

It's the same engine as the accord man and almost makes the exact same power. The proof is in the "recommendation" for premium and not "requirement". It is psychological crap, lexus did it with their 3.5L V6 in the past before reverting to regular a couple
years later. The rough running/noises are completely psychological IMHO.

Danny Boy

2x

Skidoor

You could be right in the case of feeling the engine was less responsive...but regarding the difference in engine noise I am certain I wasn't imagining that.

RDX10

Lol I obviously can't tell you what you are hearing. Just that maybe with knowing you put regular in, you became more sensitive to it? It's funny how you find something when you look for it, like how I RARELY ever seen another Sorento SX on the road before buying mine, next thing you know I see at least 1 (if not 3-4) everytime.

MTD

If you really want to argue specs...
https://en.wikipedia.org/wiki/Honda_J_engine

chickdr

The funny thing is it doesn't even list the 2016+ RDX motor. But we know it is the J35Y1

RDX10

Wow Vtec doesn't engage until 5150 RPM in the RDX? Why so high? It was roughly 4000-4500 in the 1G RDX and my 2007 MDX.

Carbon2008RDX

My 2016 RDX is a blast to drive with the NA V6 279 H.P. and 6-Speed. It’s a really a good match and very sporty when one wants it to be. Drop it in Sport Mode and it gets even better.

The 1st Gen was a 4-banger with turbo so makes sense to have the VTEC kick in earlier.

matman1215

I have a 2017 RDX and when I run regular, I can definitely tell a difference in engine noise. I've switched to 91 due to the noises. It's a loud tick when I run 87. Friends have noticed it, too.

kurtatx

It's like ChemE all over again. Great post!

Comfy

Yes, that was really informative post by Justin.

SarasotaAL

I drive 600 - 800 miles a week working my sales territory. I use regular unleaded with no issues. I also get my oil changed @ my local Honda dealer.

Himecraig

Interesting...have you tried premium grade on these trips?

awhile ago we took a 'lets see the difference for ourselves' 400mi road trip in identical Lexus rx300.
Both vehicles were bought new the same time from the same dealer.

For the trip, both tuned up same time, we rotated drivers and passengers, same loads...
the vehicle using premium was able to continue another 100mi on the trip whereas the one running with regular was on 0mi.
Traveling side by side I remember them waving and phoning frantically needing to get gas.

For this one trip the extra cost of premium was offset by the increase in range.

chickdr

That seems very unusual. I would love to know if that is common with other RX300 owners. We see no difference at all in miles/tank with premium vs regular in our 16 RDX.

Danny Boy

I too see very little milage difference in my 2016 RDX between regular and premium gas.

Doobiewah

^^^^^
I wish we only had to pay .13 more per gallon for the premium....

RDX10

We pay per litre for gas in Canada. So that .13 you see is per litre. Obviously per gallon that adds up to 0.52 difference.

Doobiewah

Thanks for the clarification...I was thinking it was an old picture...not aware you were from Canada....now looking at the post, I see the 'ca' in the pic...

But, I'd still like to just pay .13 per gallon more for premium....

RDX10

Haha all good man and trust me, I wish premium was the same price as regular! My Sorento is the first car I have ever owned that did not need premium gas. I almost feel dirty filling with regular now, but on the flip side I earned the right to fill regular since the last 8 SUV's REQUIRED premium. Yuck.

Skidoor

You have paid your dues. This reminded me that my older Murano also "was supposed to" receive premium. I recall being stuck in a traffic jam on a hot day, with a tank of regular in it, (I almost always used premium) and every time I touched the gas to move forward, I could hear light knocking...if I didnt have the window open and have a guardrail beside me, I don't know if I would have heard it.

Also, after doing some math, it occurred to me that if you stock up on bottles of octane booster when it goes on sale, you would definitely come out farther ahead dollar-wise by adding a bottle and filling with regular.

Doobiewah

I learned years ago to keep a bottle of octane booster in my 'travel kit' at all times for both my Harleys and autos. There are times, when travelling through the boonies, where the only fuel available ends up being regular. Was down to fumes on a Harley in the middle of BFE (took a scenic turn that ended up being miles more than the map showed) and had to put in a few gallons of regular to get to a 'bigger' town. Boy, did that bike run rough...almost sounded like it was throwing parts. I was lucky that it didn't actually hurt anything, once I ran some premium (this was back in the day of Chevron 'Custom Supreme' 97 Octane in the white tank, so I used that for two tanks, then went back to 'Supreme', which was 'only' 95 octane).

I don't disagree with those who choose to go 'regular', I just keep it simple for me for the peace of mind....heck, I easily pay for the difference by brewing my own coffee instead of buying at the Starbucks near work like most of my subordinates (who all love to complain about a lack of money for this and that but still buy two or more times a day there, at probably $10 a day...their call as it's their money....I'll just buy the Premium gas, instead!).