Pair of TLs

Hou-RL

At the new gas prices I think everyone will be using 87 Octane to save money.

JB in AZ

I've been using 87...maybe I can drop to 83? If I can find it?

Unobtanium

It would save me roughly $40/mo ($6 a fill up) t o use 87 instead of 93. Why on earth would I do unrecommended things to my car for $36/mo? In fact, even in kalifornia based on the memes I'm seeing of gas prices, this is a similar disparity. Noone who can afford a newer RDX is going to balk at $40/mo.

JustMe...

Just like your old Mazda, the RDX will run fine on 87. Premium is not required, like it is on the NSX. Using 87 just reduces power by a small amount and will not harm the engine.

How much are you now spending on gas per month. Last July you were complaining of spending $300 on the Mazda forum. I can't imagine you're anywhere near that with the RDX.

fiatlux

When people start asking about switching from premium to regular due to higher gas prices, that's how you can tell who overextended their budget and probably shouldn't have bought a premium/luxury car .

It's like when people buy a Mercedes, and then when it comes time to replace the tires they go with some Chinesium Westlake or Geostar tires

JustMe...

Maybe some people just like to save money. Even though they don't need to, to survive. I know several people with mid to high 6 figure incomes who use coupons and rebates all the time. Have you seen the car Warren Buffett drives? LOL

fiatlux

If they wanted to save money, why did they wait until gas prices are higher to do so? It's not like the difference between premium and regular has increased; the delta is still the same. When it's $65 vs $60 for a tank, premium is fine, but when it's $85 vs $80, suddenly it's not?

No, I don't think it's about saving money, because the money saved would have been the same when gas was cheap. It's about not being able to afford $85 a tank when they could "afford" $65 a tank.

Unobtanium

I am driving less, now, so I'm still probably at $250-300, even at todays prices. I am rather nervous to run 87 in it. The manual says pinging/detonation can result. Id rather run what's supposed to be run.

bdawwg

No one anticipated Russia invading Ukraine and what that would mean for the world. People anticipate regular seasonal price changes; it's not common knowledge what years of domestic energy underinvestment all of a sudden coming to heads with major, major geopolitical risk. People still don't understand what the China-Russia relationship means for the world commodity market going forward. I believe China is going to control the tap on many commodities now that Russia has been taken off the world market. Those commodities will go to China who will control the trade terms with the west. This is a world changing development, and there's not way people could figured it out a year ago; in fact, the latter part has still yet to be seen by the mainstream but the writing is on the wall for those of us paying attention. Now my expectation for commodity prices going forward has be scrambling a bit.

Unobtanium

It's not a new RDX, is it? Makes my point.

fiatlux

Sure, but again how does that explain the immediate (dare I say knee-jerk) reaction to switch from premium to regular to save a few bucks, when people had no problem paying those extra few bucks when the absolute cost was lower? The answer is that they could "afford" to pay the extra dollars when the absolute cost was lower, but can no longer (or at least think they can no longer) afford to pay those few extra dollars when the absolute cost is now higher. And if they truly can now no longer afford to pay the extra $5 or whatever per tank it costs to fill up on premium, I'm willing to bet they couldn't actually afford to buy these cars before.

ross7777

It’s not like there is a shortage or we are about to run out of oil. This is the market overreacting like it has before.

JustMe...

No, it's a 2014 Cadillac XTS. He must not be able to afford a new RDX, right?

bdawwg

I disagree. US oil stores are at an over decade low, not this low since 2008. People are being told to return to commuting to the office. Summer travel season. Oil embargoes. Many OPEC countries unable to ramp production. This isn't oil companies price gouging, this is an actual energy crisis and it's going to have profound effects on our economy. Gas will go higher in the next couple months, and we'll be lucky if it comes down to current levels by next winter.

No, we won't run out of oil, but the supply demand imbalance will continue to be unfavorable for at least long enough to put hard brakes on our economy. Maybe eventually prices come down as EVs pick up, but EVs are in short supply, the commodities it takes to build them will continue to be bottlenecked and controlled by PBOC, and adoption is questionable anyway in the US. This isn't a blip.

bdawwg

Sure, people buy more car then they should all the time. Someone buying a $50k car should have like a $90k salary based on the 15% rule, but its easy to finance one that is 25% grosss income and let maintenance remain hidden in the total cost. A $1 difference in octane/gallon on 10k miles a year is like a $500 difference, which isn't nothing for even someone making 90k, for not getting anything for it. But the scary thing is always its unclear how long this goes on for or how far it goes. The change from 91 to 87 quickly turns to the conversation of just going to electric.

ross7777

We will see. I still think it’s a blip. There have been many before. Covid threw everything into a mess and it will eventually normalize. Maybe not back to $2/gallon but it will come back down from $5-7/gallon.

The market goes crazy when uncertainty comes into play.

JB in AZ

Right! I used regular in my '19 RDX the whole time I owned, it. ~30,000 miles. I felt absolutely no need to use Premium. I was more than satisfied with the performance using regular. IF it had been required, I would have used Premium.

I almost always buy my gas at Costco, as apparently do many other posters here. Isn't that saving money? Anything wrong with that?

BTW, the delta between regular and premium was not much at the station in LA a day or so ago, based on the image posted here. Two cents? Oh, maybe it was four cents as their was a mid-grade. IF I had to get gas there, I might have even treated myself to premium! Of course, my next RDX won't be here until next week (I hope). AND I hope not to be in LA anytime soon! Paid $3.99 yesterday in Tucson, today I see it is $4.14!

EFR

Anxious to hear what you think of the '22. All the reports so far seem pretty good. The RDX is still on our list of six for the end of the year, assuming there are cars on lots. Don't want to overreact to todays gas prices, but if this keeps getting worse, a PHEV or EV could very well end up on our list. A down side of EV's is there just aren't that many choices available at the time, but there seems to be several on the way out.... For a variety of reasons I am just not a Tesla fan, so that really shrinks the pool. That the RDX can safely take regular is a big plus. While affordability would never be an issue for a vehicle or gas, being a cheap guy is, and I have had my fill of premium fuel cars after many years of BMW's and Land Rovers. Hope you and the wife are at least feeling 'good', or good enough. I cannot imagine being through what you all have.

JB in AZ

I will be sure to report when I get it, but I did test drive a '22 Advance.. It did seem quieter and smoother than my '19, but obviously, I didn't drive them back to back.


Thank you for your kind words. We are getting better every day. While we each still have some "issues" we are still walking, and breathing in and out every day as well. When needed, we help each other. (We've been married over 45 years!) We can't change what happened, we can only look forward. And we are able to enjoy spending some time on occasional weekends with our 21 month old grandson, who lives about 1.5 hours away...

ColoRDX

You're right there is plenty of oil in the ground of the USA. Our greedy USA oil companies don't want to pump it to match demand or exercise the 9,000 unused approved drilling permits.
Too much Wall Street pressure to pay dividends. "Don't pump, drive that price up!!!"

Texasrdx21

agree plenty in the USA, but better chances of winning the power ball before this administration reverses DJT energy independence bill.

Unobtanium

US oil is profitable at $40+, and we spent most of 2020 under that, and a fair part of 2021 barely above it. They shut down production because it was pointless. Its not fast, free, or easy to get wells producing again. Yes this is an overreaction, that's how markets work.

ross7777

There are plenty of permits for oil companies to use. They won’t as the previous post stated, until the price is higher.

Oil is a global commodity and the turmoil and uncertainly in Ukraine has spooked the markets.

We aren’t the only country with high gas prices.

Pair of TLs

Yup. Inflation is global as well, also worse than here. IMO, what's "spooked" the markets is the sanctions and petrol is the play for some quick profits.
Big Oil is doing $Billions in stock buybacks again. Q1 profits are massive. They sit on each others' BoD, you know.

A-Spec-2019

2019 RDX Aspec - I have a lack of power with both 87 & 91 also tried 94. Car is running too rich. Because, of no increase in performance I only use 87.
Oil level goes up with gas contamination quite a bit, After 12 KM it raises approx 4mm. The dealers won't acknowledge and always come up with B.S. excuse.

ColoRDX

1Wow! This a new one. Higher octane results in oil level increase?
Burning 91 vs 87 will give you a nil to no level of performance increase you'll be able to notice without formal technical measurement. Even then, it is very minor. I learned this from fellow forum member Baldeagle, post# 5 on this thread

A-Spec-2019

Higher octane didn't increase contamination. I just use 87 because no performance increase. So increase oil level is from using 87.

Unobtanium

87 will cause worse dilution than 91, typically. Makes the vehicle run richer.

Showkey

Booooooogus

rbbcpa

well said. Probably the most accurate assessment mentioned on this thread.

bdawwg

I sympathize. with a $.50 spread on 87-91, 250mi/week in an RDX amounts to an additional $325ish difference annual, so no, that's not a massive deal for most of us in isolation. That's well less than 1% of probably most of our salaries. But the price of gas has almost doubled in the last year (+40% without the war). If you drive an RDX 250 miles/week, your annual gas bill has been creeping up all year and it has now just gotten real bad. What was $30/week is now $55/week- that's 10 Spotify subscriptions per month. Plus literally every other commodity spiking, plus upcoming rate increasing. People are or will be getting stabbed to death by small increases everywhere, so it makes reasonable sense to find places where you can save a buck. Go unleaded, dont go out to eat, buy cheaper food, don't take out loans, etc etc. Every time the 87-91 debate comes up, the conclusion is always 87 is totally fine if car doesn't require higher; so going 87 sounds like an extremely easy way to start fighting back against the compound effects of inflation. What I'm trying to say is, it's not just the gas, its the gas plus everything else that are making people who may have followed the standard financial guidance start to hurt unexpectedly.

And it's a knee-jerk reaction recently for a reason, it's an actual spike is prices. https://www.gasbuddy.com/charts . This isn't boiling the frog, this is recently throwing the frog in the boiling pot; a reaction should be expected. And it's also not like its some random storm wiped out some production capacity for a bit, this is global supply chain crisis, and we've all spent 2 years being spoon fed the transitiory narrative, and it's becoming obvious to more people that prices don't just magically come down by themselves. Compound the risks and we're looking at long term risk of living with even much higher gas prices than they are today. So, I'm not about to gatekeep reactions to a very sketchy global situation in the forseeable future. I happen to believe Russia and China are geared up to intentionally break the west with commodity pricing, so I don't think this is going away any time soon.

Unobtanium

Just because you dont understand how modern DI turbo engine management works doesn't make something bogus.



When you run 87, the engine is going to have a higher knock count, and will pull more timing on hard throttle application. This will result in a richer mixture in the cylinders.


This has been shown through datalogging, UOAs, and subjective "hmmm...on 91+ my oil doesnt smell as fuel like and the level isnt higher" type observations.

tecwerks

Who Cares? I will be replacing my 2022 way before the factory warranty ends and purchase another or something else. I love people that obsess over something that really does not matter to most car owners.

Unobtanium

Big market for low mileage cars. You'll do well.

ColoRDX

Another who cares vote. Acura is on the line for 6 years or 70K miles. If 87 octane was a real no, They would state 91 Octane ONLY but, they don't.

russianDude

They only stated that 87 will not damage your engine or void your warranty. 91 is recommended if you want to get performance the car was designed for.

russianDude

The spread here at costco is $0.20 most of the time between 87 and 93.

JB in AZ

Believe it or not, some people are fine with the ~250 HP it likely makes using 87.

Personally, I wish the RDX had a hybrid option, fuel economy focused, not performance. 225-250 HP, 30+ mpg. It CAN be done, Toyota does it on the Highlander Hybrid, a 3 row that gets 35+ mpg. 243 hp. Certainly, with the smaller footprint, the RDX would do real well with a hybrid.

Baldeagle

Run richer? Do have any links to a site that explains this? I'm 99% sure that does not happen.

Here is my understanding. Knock is caused by a secondary ignition inside the cylinder. The primary ignition starts with the spark plug. As that flame kernel expands across the cylinder, it compresses the unburned fuel in the cylinder. In a spark plug ICE, fuel takes a several thousandths of a second to burn. It is not instantaneous. Anyway, this expansion of the flame front across the cylinder behaves somewhat like a shockwave from a bomb. It has a pushing effect. This pushing effect increases the compression of the unburned fuel along the perimeter of the cylinder. That extra compression is enough to raise the temperature of the unburned fuel above its flash point and it detonates. In effect, the unburned fuel compression ignites. What the cylinder gets are two separate “booms” inside the cylinder. One from the spark plug (desired) and another very shortly after that from compression ignition (undesired). This secondary ignition also has its own “shockwave.” When the two shockwaves collide, it massively increases the pressure inside the cylinder. The pressure spike is so great that it pushes the valves sideways in the cylinder head (ping) or worse, it pushes the piston sideways in the cylinder (knock).

By retarding the ignition timing, the ECU starts the primary ignition closer to top dead center. By starting the ignition later in the compression stroke, it pushes some that burn-time deeper into the expansion stroke. Once the piston passes top dead center and starts moving down the cylinder, cylinder volume increases and pressure rapidly decreases. That decrease in pressure prevents that secondary compression-ignition from ever happening and eliminates the engine knock.

If I recall, engineers want the fuel to fully combust before 18° after top dead center. Any fuel that still burns beyond that point/time no longer pushes down on the cylinder as it expands. The more the ECU retards timing, the more of that fuel combusts during the power stroke. That is what decreases efficiency (torque). The same amount of fuel ultimately combusts, but less of that heat expansion gets converted to work. Circling back, the ECU does not increase the fuel mixture when it retards timing. It simply starts the ignition process later in the cycle, and pushes the point in which the secondary ignition might happen into the power stroke, where it really can't happen anymore.

Also, octane is about activation energy. How much energy does it require to start burning? How much heat does it need to self-ignite? Higher octane fuel needs more energy (heat) to start burning. It resists burning more. Therefore, it can handle more “perimeter compression” from that expanding flame kernel than lower octane fuel before compression ignition begins. For every few degrees more before top dead center the ECU can ignite the fuel, that much more fuel combusts before that 18° after top dead center point. That is how the RDX makes 272hp on premium versus 252 on regular.

Anyway, if you can provide a link that supports your richer fuel mixture statement, I'd like to learn about it. Thanks.