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Regular or Premium Gas

133K views 179 replies 68 participants last post by  elvisfan 
#1 ·
I am looking into purchasing a 2016 MDX Advance Package and the specs say premium gas is recommended and the dealer says regular is fine. What is everyone using in theirs?
 
#4 ·
High compression engines are more sensitive to variations in octane. In the case of the Acura MDX, the ratio is 11.5:1. This is "high," considering this is not a supercharged or turbocharged engine. By way of comparison, a BMW X5 has a compression ratio somewhere around 10:1.

A good "youtube" on explaining what compression ratios are, and why they are important can be seen here. (no, that kid is not me - I have no idea who that kid is) but he does go on and on in a very detailed manner.

https://www.youtube.com/watch?v=nveqCMNTth0

But basically, using a lower octane fuel will probably combust before the cylinder reaches full (mechanical) compression (and sometimes without the spark plug actually causing the ignition) - this is called "knock." All knock is, is an unregulated explosion in your engine - not explosion as in "your engine blows up" but unregulated - as in, before the piston fully compresses the fuel-air mixture.

Knock may not be a big deal in the short run, and for a variety of reasons - in part because the vehicle computer will probably just adjust engine timing to reduce/eliminate the knock. But in the long run, and especially if your car is under "load" (e.g. always driving up hill, always pulling a trailer) then you may be causing long term damage. However, as the vehicle adjusts its timing to account for the lower octane fuel - you may experience lower power and lower fuel economy. This may ultimately defeat or cut in to your reason for wanting to use regular in the first place. It may be interesting to do a couple tanks of premium and of regular and compare your mileage (pen and paper method - not the trip computer).

And while I do not know this, I would not be surprised if the vehicle computer stored "fault codes" for knock and low octane gas... and that may cause you warranty difficulties if you ever had a serious engine problem.

But this is all just my superstitious speculation.

As for where I get my gas, I just buy premium from Costco. I don't get into the "additive" hype of some of the major brands... and even if they are proven to be true, it is really just a fuel filter issue... just my two cents.
 
#7 ·
As for where I get my gas, I just buy premium from Costco. I don't get into the "additive" hype of some of the major brands... and even if they are proven to be true, it is really just a fuel filter issue... just my two cents.
I also regularly fill up at Costco, but only recently as they have received the Top Tier certification which is more of a cost/marketing thing, but it does show that they have A LOT of additives. These additives are added at Costco while the fuel is being delivered from the tanker.

I only use Top Tier gas, Costco is convenient for me, but if I'm on the road, I almost exclusively use Shell V-Power or Texaco 93.

Finally, while detergents are hype, I did have a 2002 Acura MDX and used Murphy gas for about a year, and I developed a bit of a shudder at 70K miles and took it to the dealer thinking it was transmission, differential or some other driveline related issue and the dealer said there was no issue but they felt a little hesitation and took the head off and it had excessive carbon build up. So I paid them $200 or whatever to clean it, it did perform better (placebo maybe) and the hesitation/shudder was reduced. The top tech told me to stop using grocery store gas. He could've been feeding me a line of crap, but octane aside, the Top Tier gases don't really cost more, and Costco is actually the cheapest in our town.

Finally, my friend has a 2011 Land Rover LR4, it has 60K miles and an extended warranty. My friend puts 87 octane grocery store gas in and the SUV will not go over 40 mph now and Land Rover states all the injectors are shot "due to poor gas" and they are not handling it under warranty and it is $5,500 to replace all the injectors and clean the head. She's in the fight of her life against Land Rover to try and get them to right it as she has only had the car for 20k miles, she bought it from that dealer certified with the warranty, etc.

So all that said, it's just not worth it. Especially with gas so bloody cheap right now, what's an extra $0.30 per gallon for 91/93 octane as well as a more premium Top Tier gas.
 
#5 ·
I follow the manufacturer's recommendation - premium. I also follow their other recommendation of using 'Top Tier Detergent Gasoline'.

Following the manufacturer's recommendation makes much more sense than following the recommendations of random people on the internet who aren't automotive engineers or the people who designed the engine used in the MDX yet who are all too willing to offer their opinion anyway (I include myself in this category).

If you're thinking of buying the proverbial $50K vehicle where you're already paying extra money for certain niceties (leather, sunroof, etc.) and performance, it doesn't make sense to sweat the small point of the extra cost for premium gas. If you can't afford the small difference for premium gas then you probably can't really comfortably afford to buy the MDX in the first place.

If nothing else, do the calculations yourself of the actual cost difference of premium vs regular based on the miles you drive per year to quantify this. You might be surprised to find it isn't a terribly significant cost. Some people pay more for decorations for the MDX (running boards, foglights, chrome bumper things, etc.) than they do the extra cost of premium gas.

Oh - and don't ever inherently believe what a salesperson tells you. Not only do they usually not really know what they're talking about, but they'll usually tell you whatever they think you want to hear if they think it'll help close the sale.
 
#8 ·
I follow the manufacturer's recommendation - premium. I also follow their other recommendation of using 'Top Tier Detergent Gasoline'.

MDXSTANG, how do you determine if the gas you use is "top tier detergent gasoline"?

I use 92 octane at Thortons most of the time. I think it is recommended you need 91 octane or better so I don't see the point of using 93 octane which most gas stations use for premium gas. I am sure all 93 octane is a top tier detergent.
 
#6 ·
Premium is the only way to go - it's a 'pay to play' cost you'd want to accept when moving to higher tier cars.

Tires cost more for larger wheels and higher performance,
Maintenance schedules and costs,
higher quality fuels and fluids for higher performance motors...
and so on...

I know, I know there's lots of debate on the cost vs quality (and necessity) of these things, but science doesn't lie as per the post above - higher compression = higher octane fuel (more resistant to knock & detonation)
 
#10 ·
It's worth noting that NOT being on this list doesn't mean your gas is bad, it just means you didn't go through the certification process and pay money for this certification. However, being on this list means that a specific amount of additives above and beyond the legal requirements is added and that the gas from an additive standpoint is considered good.

I refused to buy Costco gas before they were on this list as I had no idea if they were adding any specific additives, but once they got on this list, I immediately switched to them without worry.
 
#13 ·
Green - Here's the actual text in the owner's manual - note the key word 'endorses' rather than 'requires' -

■ Top tier detergent gasoline
Because the level of detergency and additives in gasoline vary in the market, Acura
endorses the use of “TOP TIER Detergent Gasoline” where available to help
maintain the performance and reliability of your vehicle. TOP TIER Detergent
Gasoline meets a new gasoline standard jointly established by leading automotive
manufacturers to meet the needs of today’s advanced engines.
Qualifying gasoline retailers will, in most cases, identify their gasoline as having met
Driving
“TOP TIER Detergent Gasoline” standards at the retail location. This fuel is
guaranteed to contain the proper level of detergent additives and be free of metallic
additives. The proper level of detergent additives, and absence of harmful metallic
additives in gasoline, help avoid build-up of deposits in your engine and emission
control system.
For further important fuel-related information for your vehicle, or on information on
gasoline that does not contain MMT, visit Acura Owners at owners.acura.com In
Canada, visit Acura Canada for additional information on gasoline. For more
information on top tier gasoline, visit Top Tier Gasoline.
 
#16 ·
I have seen recently that the cost between premium and regular is out of whack at certain gas stations. Which is generally because of the low volume they sell, but it could be people like me just blindly buy premium.

Whatever the case, I have started to use cheap gas finding apps like GasBuddy. I have saved .40 cents a gallon by driving to the next station.

Please always enter the premium price in the app when you see it!

For reference, I have had an MDX since 2008. Bought the 2015 last year. Always used premium.
 
#17 ·
FWIW, I had a 2008 Pilot EX-L that also recommended premium (similar engine to earlier MDX's). In 7 years and 100,000 miles I always used regular. I never had an issue as the computers these days are very good at adjusting the timing to compensate. There was a slight decrease in performance but that could have been due to the pile of cash I was saving by using regular...LOL! Seriously though, this was the family car so performance was not the purpose. I've had the 2016 MDX for a few months now and have yet to put in premium.
 
#18 ·
FWIW, I had a 2008 Pilot EX-L that also recommended premium (similar engine to earlier MDX's).
The 2008 Pilot recommends regular fuel only recommends premium when towing. The MDX recommends premium all the time. We had a 2006 Pilot before our 2013 MDX. Used the recommended fuel in the Pilot and MDX. You could also change oil every 20k miles to save a few more dollars.
 
#19 ·
Correct. The Pilot is a regular unleaded vehicle. The engine compression is also lower than on the Acura MDX. But again, if you accept that the ignition timing will adjust to account for the lower octane (which is generally true, unless you place the engine under hard load wheel towing or "flooring it,"- then you seem to be acknowledging that your gas mileage will also suffer... so that 10% cost premium you save on regular unleaded gas might just get eaten up by 5-10% less MPG and lower performance... and long term engine wear... of course, that is if it required premium in the first place...
 
#20 ·
then you seem to be acknowledging that your gas mileage will also suffer... so that 10% cost premium you save on regular unleaded gas might just get eaten up by 5-10% less MPG and lower performance... and long term engine wear... of course, that is if it required premium in the first place...
Interesting, please explain how retarded timing results in 5-10% less MPG. I'm genuinely interested. Also, does that have something to do with the engine wear? How are those connected or are those two separate things? BTW, my owners manual only recommends (not requires) premium, but maybe that is only on the Base model.
 
#21 ·
my owners manual only recommends (not requires) premium, but maybe that is only on the Base model.
Here's what the manual states - it's not just an empty recommendation -

Use of lower octane gasoline can cause occasional metallic knocking noise in the
engine and will result in decreased engine performance.
Use of gasoline with a pump octane less than 87 can lead to engine damage.
Lower performance implies that one will compensate for it by giving it more gas which adversely affects gas mileage which will negate some of the savings by getting cheaper non-premium gas. Whether it's significant or not I don't know since I haven't scientifically tested this and neither has anyone else here.

I'll stick with the recommended fuel of premium. I knew of the recommendation before buying the vehicle. I already paid for a higher performance vehicle, as opposed to a cheap econo-box, and the extra fuel cost is a part of that. When calculated out to the real additional cost per year it isn't much.
 
#23 ·
That is a great video. I totally agree, especially with regard to the discussion of brand names and detergents. I only wish they had carried it a step further. At 8:18 the expert explains that he would only use premium (in his corvette) if he was "going around a race track." But the reporter doesn't ask "why?" (especially in light of the preceding discussion he has about the Chevy Cruz. At 13:50 they do an emissions test (again on the Chevy Cruz) and find that when using premium fuel in a regular fuel car, "that there is unburnt fuel going out the tailpipe." The "premium fuel is not getting used up like it would in a premium fuel car." I only wish they had done the exact same tests in reverse (using a premium car like the experts corvette and then running it on regular gas!)... so it is a good video, but it addresses a different question than we have been discussing here.

The good thing about the internet and experts is that you can find something to validate any point. For example, I could say, "hey, look at this article from Car and Driver Magazine:"

Regular or Premium? - Feature - Car and Driver

Which essentially (after explaining everything) concludes: "Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump."

Oh well. Hopefully whatever folks do will work out for them... and again, hopefully they never have serious engine issues... since Acura wouldn't hesitate to void the warranty when they pull the engine codes... I suppose the intrepid owner could seek written confirmation from Acura that they would not void the warranty... I would take that as pretty good evidence Acura doesn't think it matters.
 
#25 ·
My wife and I both drive E46 BMWs; hers a 325i and mine a 330i.I I use premium and she uses regular. While hers underperforms, I have never heard it ping. I'm sure it's not being damaged in any way.
 
#26 ·
On my 2005 MDX, I would use cheap premium for 4 or 5 fillups, then do 1 with Top Tier. After 135K miles I am satisfied with the results. No rough idle or misfire or injector clogging.

Tried the same on my 2014 with the GDI engine, but I can feel the difference in performance and get better MPG with Shell Premium. I still hate to pay the 50 cents a gallon extra, but I'm at 43,000 miles and running out of warranty soon, so I don't want to screw myself by fouling the expensive injectors. Lots of reports of GDI problems when not using top tier.

One cheat that I do use sometimes is to add 5 gallons of 87 octane top tier on top of a half full tank of 93 octane. Results in about 91 octane, which is the recommended number. I then go treat myself to a Happy Meal with the two-fifty I just saved.

Life is good.
 
#28 ·
On my 2005 MDX, I would use cheap premium for 4 or 5 fillups, then do 1 with Top Tier. After 135K miles I am satisfied with the results. No rough idle or misfire or injector clogging.

Tried the same on my 2014 with the GDI engine, but I can feel the difference in performance and get better MPG with Shell Premium. I still hate to pay the 50 cents a gallon extra, but I'm at 43,000 miles and running out of warranty soon, so I don't want to screw myself by fouling the expensive injectors. Lots of reports of GDI problems when not using top tier.

One cheat that I do use sometimes is to add 5 gallons of 87 octane top tier on top of a half full tank of 93 octane. Results in about 91 octane, which is the recommended number. I then go treat myself to a Happy Meal with the two-fifty I just saved.

Life is good.

unbelievable :runaway:
 
#30 ·
engine knock is a thing of the past. Modern engines have knock detection and self-adjusts it's timing to eliminate knocking.
That's why it is "recommended" for premium fuel, not "required". Old MDX "required" premium fuel.

Personally I found no big difference in performance impact, nor fuel efficiency with my '16 MDX. And at 15~20% price difference at the pump, I always fuel up regular 87 except for when I'm towing.

On my '13 RDX though, the difference in performance/fuel-efficiency was huge, and I had always used premium fuel.
 
#32 ·
Both the MDX and the new Honda Pilot have a Compression Ratio of 11.5 : 1 which is quite high, I believe the only difference between the 2 is the way the engine tuned. Premium just hit $.66 over Regular at one station where I live I'm going to try mid grade and see if theres any differance I can notice.
 
#35 ·
Chezez guys, you forked out over 40-50K for a vehicle and now counting pennies. Let's see: the regular gas here in Canada where I live is. $0.85 c/litre. The premium is $0.97. The spread is $0.12 I usually fill up at around 50 litres. Oh my, I save $5.00 if I use regular. I know that times are thought now but not that thought! Some of you spent more per day for coffee and cigarettes....
 
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#41 ·
It's not about affordability. I'm sure most MDX drivers can "afford" much more than a MDX.
It's about with it is "worth" to you. I bought the MDX because I thought it was worth the price I paid. I don't buy premium gas because the benefits isn't worth the extra cost to me. However, the benefits are definitely worth the extra cost to many. To each their own.
 
#37 ·
Are you talking about the price in litres or gallons? Looks like a gallons to me, then it's about 4 litre in a gallon, so $0.70 x12 gallons(approx 48 litres) = $8.00:surprise:
But if you are paying $1.96 for a litre of regular - then you are screwed no matter what!>:)
 
#38 ·
Because Acura makes horsepower/torque and mileage claims based on certification with premium fuel, they must recommend premium fuel in the owners manual. Note that the Honda Pilot uses exactly the same engine but is certified with regular gas. Their power ratings are lower not because the engine is designed differently, but because those power figures are calculated using regular gas, which for Honda is an important competitive marketing consideration. Honda does recommend premium fuel, however, if you use the Pilot for towing.

Some car manufactures require (not recommend) premium fuel, because the engine longevity (ie, ping and detonation concerns) would be adversely effected using regular gas. This is not the case with the Acura V-6 port fuel injection/direct injection engine. It's simply a certification issue.

Hyundai's Genesis models used to post separate power figures for various engines using regular gas and premium gas, so the customer could make up their mind.

Personally, I have noticed my car seems to perform better and smoother on premium fuel, especially driving up I-70 through the mountains on a hot day. I think it comes down to one of those "cost/benefit" analysis problems. Whichever side you come down on, it's nice to have the option.
 
#39 ·
Slow down. The fact checkers are very busy with other tasks right now, but I can wing it on this one. The engines and drivetrains in 3rd-gen MDX and 3rd-gen Pilot are very similar, probably more similar than in any previous generation, but they are not "exactly the same engine". There are subtle differences in hardware, as can be determined with a quick look at parts diagrams ( or just peek under the hoods... there is one of each in my garage ), and tuning matters. They are tuned differently. Whereas modern computerized engine management systems are adaptive, I don't believe the MDX engine will adjust to the same tuning as the Pilot engine if you feed it regular unleaded, or vice versa. But either engine will adjust to mitigate pre-ignition as required.
 
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