tealking

I'm interested in the RDX but am put off by the meager gas mileage and premium fuel. What would happen if one used regular unleaded on a regular basis?

seevemonka

You would get less gas milage and less performance. Luxury cars, especially the rdx; run on very high compresion ratios. High compresion is designed to go with high octane gas. This is how you get maximum performance out of the engines. I drive a bmw 3 series. If i put in regular type of gas, the car doesn't run that well. You will average about 20 mpg(mixed driving). Once the car gets broke in. This is average for this class of veichcle. In my opinion, this car is underrated in power. I think the rdx, gets closer to 260 hp/260 torgue, minimum.

jbinnyc

i also think you void the acura warranty by using regular & hurt the engine. i just got my rdx & getting 22.5 mpg. this vehicle is built solid & has huge amount of power.

crazymjb

The regs are there for a reason, especially with a forced induction engine. If you don't want to pay for premium don't get one. We get too many threads after people have bought their cars (So far I have seen in RDX, TL, and on another board MDX sections). Premium only. You can possibly get away with a lower grade fuel but you will take a cut to mileage, performance, and possibly damage your engine.

Mike

mvwood

on the flip side, using higher rated gas (like 94 octane) will make things even better, right?

Fishbulb

No. Running higher octane than spec is like Homer putting speed holes in his car.

Skeandhu

Similar debate hya:

https://acurazine.com/forums/showthread.php?t=178

SolidState

Not again. Do a search on the forums. There are a lot of people asking the same question. This question should be in a FAQ list.

coldbuttfood

IS THE 22.5 CTY/HYW COMBIND?

ARE U GOING BY THE TRIP READ OUT?

TRY CALCULATING IT WITH OUT THE TRIP READ OUT.

HOW MANY MILES DO YOU HAVE ON THE RDX?

I HAVE ABOUT 4000 AND CITY/HYW IS AROUND 18.7 IF I CALCULATE IT AND 21.6 USING THE TRIP COMPUTER ON MY RDX..HAVE A DAY! CBT

mvwood

speed holes, eh? Will that work too?

jbinnyc

It was combined, but 95% highway. I put 900 miles on it within the first five days of purchase last week. It was based on the trip read. I am going to drive it Sunday & Monday for a few hundred miles & I will see how it calculates on a full tank.

black label

2 things will happen first it will be cylinder detonation, then when you bring it to Acura, they will drian your tank realize you were putting in cheap fuel and explain why you will pay for the repair.

thexster

I will only use premium, but Acura do only "recomed" it , its not a must or warranty may be waived, also performance will suffer.

neo1738

as stated earlier, open the gas door and read

PREMIUM FUEL ONLY.....not recommended!

sasair

Fuel Recommendation
Your vehicle is designed to operate
on premium unleaded gasoline with a
pump octane of 91 or higher. If this
octane grade is unavailable, regular
unleaded gasoline with a pump
octane of 87 or higher may be used
temporarily. The use of regular
unleaded gasoline can cause metallic
knocking noises in the engine and
will result in decreased engine
perf ormance. The long-term use of
regular-grade gasoline can lead to
engine damage.

Fishbulb

As soon as I've done the first oil change, I'll be switching over to 89. I don't anticipate any problems. I've also read that when tested by inspectors, the blend on the mid-grade often significantly exceeds the 89 minimum.

If there's a mileage penalty, or a noticeable performance loss, then I'll go back up to 91.

crazymjb

No offense, but thats just plain stupid. I see people always trying to penny pinch and shit like that, and it pisses me off. The engineers DESIGNED it to run on a certain type of fuel, why even take the risk, especially with a forced induction engine. Why wait until the first oil change, you want to play Russian roulette with your brand new engine using Honda's first attempt at a turbo charger on an American production vehicle go right ahead. I don't know why I care, I guess I just don't like it when people play engineer.

Mike

Fishbulb

No offense, but I could give a flying leap what you think. I didn't ask for your approval or advice.

crazymjb

I know. I am making a point, you don't need to care. You spent 36K on the car, time to experiment, your dollar.

Any engineer will tell you that you should be using the recommended octane, even the cheap ones (see: cartalk.com). Its your money, do with it what you wish. If the vehicle was designed for running on 89 that is what it would say in the owners manual, not that regular usage of lower grade could result in damage as well as decreased performance. Is this a guarantee your engine will be damaged over time? No. However, 91 vs. 89 is cheap insurance.

Mike

Fishbulb

Why do you care so much? If I want to fill it with jello, and run it off a cliff, it doesn't affect you in the least. I'll do as I please.

crazymjb

And by all means feel free to do so... The overall thread annoys me, and the fact that those who bought a car that calls for a certain octane would go off playing engineer annoys me. As I will say again... the vehicle was designed for the use of 91 or greater octane... why would you take the risk of using less to save a truly minimal amount of money? Why don't you explain that to me.

Mike

007TL-S

Do yourself a favor , buy a KIA SANTAFE

SolidState

Mike, let Fishbulb do what he thinks is best. I wouldn't recommend what he wants to do but this is a forum and people can post opinions and weight recommendations. Lets just hope most people are smarter than fishbulb.

Not sure why anyone would pay over $37K for a car and then try to save a few cents on gas.

jbinnyc

mike, i also know that anyone that puts in something less than 91 will damage their engine. but we live in a free country & we have all types of people. smart ones, stubborn ones, geniuses, & not so bright ones. what we all should do is revisit this subject say 12 - 18 months from now and ask those of us that put in 89 octane how well their rdx is performing or how well their first maintenance from acura went. i think that will be a great forum & thread to read. if the engineers that develop our engine are wrong & premium is $3.50 again; i may be influence by those that did well with 89 or jello for 12 months. but for now, i will take the advice of the engineers. but i might take fishbulb's advice on a later datel. that is what i love about these forums, we all learn something .

crazymjb

In all likelihood no ill effects will be seen in the near future... I do know from talking to people with other Acuras that there tends to be a noticeable difference in economy and performance if they put in lower than recommended octane.

That said, the knock sensors work by detecting knock, and are not always capable of adjusting around it. In addition, the random knocks that must be detected do add up...

I am not saying he can't do it... I am saying to spend 37K on a car and then intentionally hinder engineered in performance, as well as risk your cars longevity, all to save a few bucks, is beyond my logic... hence I think it's stupid.

Mike

creativeguy

I've been putting 87 octane in my 96 Integra GSR for years with no ill effects. The owners manual states that super is recommended but that if regular is used the computer will adjust and reduce performance.

What does the RDX manual state? Do they use the word "required" or "recommended"?

Madison3

Page 278:

Fuel Recommendation
Your vehicle is designed to operate on premium unleaded gasoline with a pump octane rating of 91 or higher. If this octane grade is unavailable, regular unleaded gasoline with a pump octane rating of 87 or higher may be used temporarily...(edit)...The long-term use of regular-grade gasoline can lead to engine damage.

Edited because I wasn't cutting and pasting properly...

sasair

Hmmm....that sounds familiar....

c_hunter

Disregarding the "damage" aspect, I think the big issue is retarded timing when you run lower octane. This will reduce peformance and likely, MPG as well. For the measly $80-100 savings per year (which may be offset/reversed by lower MPG) I don't see any reason to run less than premium fuel.

SolidState

Also, depending on the MPG loss, you might not be saving anything. Does anyone have stats for MPG vs Octane?

loulinjai

Fishbulb, you purchased a product thats yours, and you can run it on whatever you want. I think mike is just trying to be nice and help you out. i have lots of buddies thats are mechanics and i am a chem engineer as well. honda products have been known to be reliable. i dont think a manufacture will recommend spending more money than you have to. knocking really kills engine components in a motor. computers are programmed to minimize damage, but there are programmable limits. sauceman over at the tsx board did a 87 vs 91 thread, in my opinion is really good with real good real life results. you can run diesel in your car and nobody would stop you. but most drivers on here see a MPG suffering which justify the cost of regular vs. premium gas anyways. motor parts aren't expensive these days and fixing them at high labor rates are going to cost you if anything breaks down, which may cost way more than a savings of different types of gasoline. you may run into reliability problems in the future if you plan to keep the car for a long time with regular gas. just my opinion

mvwood

OK, so I've had the car a month and got through my first tank of gas (drive only on weekends, unfortunately).

Gas mileage was around 20 or 21l/100km (11-11.7 mpg) for much of the month when it was mostly stop and go traffic, and dropped to I think 18.8 (12.5mpg) after some higway driving and late night city streets.

Filled up with premium, and right away I've been getting way better mileage than before (about 17l/100km - almost 14mpg - in stop and go). I have always been heavy on the turbo, because let's face it, that's what makes the car fun.

My gut tells me the dealership filled it up with regular and that must be the reason the mileage was so bad.

How bad is this for the car for its first tank? Is there any point in complaining to the dealer?

sasair

Why would an acura dealer even have regular fuel?

mvwood

no idea, but I have no other way of explaining this. Why would gas mileage get so much better from filling up? If anything I was harder on the turbo yesterday than I was previously.

c_hunter

OK -- I am going to take a wild guess because this has been the case before. Did you reset your trip meter when you filled up, thereby resetting the average MPG computation? This can give the appearance of a major jump in MPG if the initial driving conditions right after the reset differ greatly from what was established with the previous average.

The other red herring is due to the fact that the vehicle's first tank of gas often gets a lot of atypical idle and low-speed driving events, which can skew the average down.

creativeguy

I wouldn't make any judgements based on the first tank. When I picked mine up last night we sat in the lot with the engine on for 1/2 hour while the sales guy showed me the ropes. That won't help the MPG much.

Fortunately there are about 10 different readings you can choose from on that display. Just watch the sh-awd or tire pressure for a while and forget about the MPG

mvwood

yeah, restarted the trip meter, so maybe that's it, but the weather has been about the same the previous month when I drove (sometimes a bit of rain, no snow).

mvwood

heh. unfortunately, I got the base (the car is more expensive in Canada and the tech was not quite worth it IMO), so all I got to play with is the mileage.