Octane Rating

[helen_92630]

Way earlier in this thread, MikeM mentioned as a side note, "for example, if the car was fueled with regular that only had an octane of 85 RON (which is actually available in some areas of the US)."

Here in the north front range of Colorado where we're at about 5000 ft altitude, the gas stations sell 85/87/89 rather than 87/89/91. This also seems to be the case in neighboring high-altitude states (Wyoming, Utah); when you go down to lower altitudes (in other states), the higher octane ratings are sold.

Both the Honda dealership and the Mazda dealership here have told me that this is because 85 at high altitude is more or less equivalent to 87 at sea level, and so it's perfectly fine to put 85 octane gasoline in the vehicle here in Colorado. Thoughts on this?

I also found the theme of name brand gas vs. cheaper gas to be interesting; my dad always used to insist on using Union 76 gasoline (in California, they don't have it here), whereas I've always thought gas was gas was gas, and just gone with the cheapest station (our local grocery store usually). Why is/isn't name brand gas better, and has any testing been done which demonstrates this?

Thanks.

 

[TURBOJ1]

I don't have a CX-5 so forgive me.....I do have a 5th gen Maxima and I do get more MPG's with 91 VS 89

 

[Beefy]

When I had a 2012 RAM 1500 with a 5.7L HEMI (390HP / 407 Torque). I used the recommended 89 octane. Then tried 87 (made a slight knocking on hills), also 91 Shell which has no Ethanol and even Chevron 94 which doesn't have Ethanol. I saw at best 3% difference in better fuel mileage going from 89 to 91/94. That could have been a tailwind for all I know. Save your money, use what is stated on the door as everything else is a placebo effect at best.

The problem is, E10 87 RON can be pretty nasty fuel. Since the ethanol provides a substantial bump to the RON, the remainder of the mix can theoretically be really low quality stuff. Thus, I run Shell 91 ethanol free and the placebo is delicious.

Now, i have no problem puttin in name brand 87s, however, i cant stop thinking if mazda did a false advertising on the fuel type needed in cx 5. Its never mentioned that cx 5 requires specific name brand gas to run smoothly.

False advertising is a bit of a stretch. Frankly, I can't understand why someone would pay $30000 for a car, then skimp on fuel. Particularly when the best feature of this engine is its unusually high compression ratio.

 

[sussig]

The problem is, E10 87 RON can be pretty nasty fuel. Since the ethanol provides a substantial bump to the RON, the remainder of the mix can theoretically be really low quality stuff. Thus, I run Shell 91 ethanol free and the placebo is delicious.



False advertising is a bit of a stretch. Frankly, I can't understand why someone would pay $30000 for a car, then skimp on fuel. Particularly when the best feature of this engine is its unusually high compression ratio.

mazda salesperson said cx needs 87 and up. owner's manuel says regular unleaded only. i gas up my cx5 with 87 regular unleaded, whats wrong with that. cx 5 engine is made to run on any regular unleaded gas period ? however, my cx5 has been in the dealer twice for warranty repairs in the last 6 months and that really threw me off. if cx 5 cant handle all brand of regular unleaded gases, then mazda should have mentioned it in the fine print. FYI, not everyone paid $30,000 for their cx5. i got mine for $25,000 with moon roof package. not to mention that u can get the sport model startin at $22,000. thats about the same pricing range for honda crv and toyota rav4. i still own my honda crv 2005 and has never brought the car in for warranty repairs since i owned it and i been using the same type of gas that i put in on my cx5. needless to say, im a bit disappointed.

 

[CX-SV]

Per 2013 Mazda CX-5 owners manual:

Your Mazda will perform best with fuel listed in the table.
Fuel Octane Rating* (Anti-knock index)
Regular unleaded fuel 87 [ (R M)/2 method] or above (91 RON or above)
* U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) could cause the emission control system
to lose effectiveness. It could also cause engine knocking and serious engine damage.

 

[jjw6455]

I always tried to stick with the brands recommended by many of the manufacturers: http://www.toptiergas.com/index.html

 

[Beefy]

mazda salesperson said cx needs 87 and up. owner's manuel says regular unleaded only. i gas up my cx5 with 87 regular unleaded, whats wrong with that.

Because 87 is the bare minimum, simple as that. If you are buying marginal 87 that is high ethanol and full of crap, it isn't good enough.

Honestly, its people like you who are the reason that Mazda didn't bring the 14:1 Skyactiv to North America. Just buy better gas and be done with it.

 

[sussig]

Because 87 is the bare minimum, simple as that. If you are buying marginal 87 that is high ethanol and full of crap, it isn't good enough.

Honestly, its people like you who are the reason that Mazda didn't bring the 14:1 Skyactiv to North America. Just buy better gas and be done with it.

perhaps u should move to europe to get ur precious 14:1 skyactiv.

 

[IronMan0737]

So, on a different note (has this not been addressed??), what's everyone's favorite brand of 87? After 6 different cars and 16 years of driving, I know that differences exist.

Example: Sunoco seems to burn more explosively, whereas BP burns very smoothly at idle but can slow RPM revving a tad.

And this varies from car to car (make), but what brand of 87 does YOUR CX-5 like? (Cool, dry climate people need not respond)

 

[CX-SV]

Chevron regular 87, 100% of the time used in my CX-5 2.0L, and it meets requirements in owners manual.

 

[Beefy]

perhaps u should move to europe to get ur precious 14:1 skyactiv.

The worst comeback I have heard in 17 years on the internet. Kudos.

 

[sussig]

The worst comeback I have heard in 17 years on the internet. Kudos.

hey...jerk store called. their running outta u. ur simply their all-time best seller.

 

[Beefy]

OK, that genuinely made me chuckle, even if it was unintentional irony.

 

[metalfab]

So, on a different note (has this not been addressed??), what's everyone's favorite brand of 87? After 6 different cars and 16 years of driving, I know that differences exist.

Example: Sunoco seems to burn more explosively, whereas BP burns very smoothly at idle but can slow RPM revving a tad.

And this varies from car to car (make), but what brand of 87 does YOUR CX-5 like? (Cool, dry climate people need not respond)

For 25+ years of driving I have used Chevron 87 most of the time. When we do long road trips Petro-Can as Chevron is not available.

 

[nXt]

I use Costco 87.

 

[IronMan0737]

There aren't many Chevrons around where I am, but I will be trying Sunoco, Shell, and BP in the next month plus. I will report back with any observations. Ideally, the car would like all three equally, but I would be surprised if that was the case.

 

[CC58]

I'm in the camp that running 91 octane will improve performance and mileage. I disagree with CX-SV here, SkyActiv-G is great, but it doesn't prevent knock.

Our USA CX-5's run 13:1 instead of 14:1 so we are able to run 87. That doesn't mean that they don't knock running 87 octane, or prefer running crappy gas. The engine knock is more simply more tolerable at 13:1 and won't damage the engine. Mazda intended the original SkyActiv-G engine to run on premium fuel. We can't be trusted over here to run 91 all the time, so we get a lower performance Skyactiv-G.

Your in AZ and if anyone would see knock it would be you in the summer. In temperatures over 100 degrees or if towing, I would consider higher octane gas if I heard a hint of knock.

Many performance cars suggest high octane gas, but allow low octane to be used. Usually stating performance will suffer with low octane. This suggests CX-5 would get better performance on high octane. I am sure the CX-5 has a knock sensor and adjusts timing if knock detected.

A good test would be to fill up with 93 octane, disconnect battery to reset computer, and take CX-5 to the 1/4 mile track and see what it will run. Of course, you need to do a baseline track test first.

 

[pjensen641]

Why don't you guys download DashCommand, get a $20 bluetooth OBD dongle and see for yourself if you have knock with lower grade. This winter I tried an experiment and saw essentially no difference in timing retard between 87 and 91 straight gas. The only time I see it pulling a degree or two of timing is around town at low RPM (1500-2000) and high load partial throttle cruise. The KR numbers for 87 vs 91 were less than a degree difference. I saw no KR at higher engine speeds and loads when accelerating. I plan to repeat the study again once the heat of summer rolls around. However, I would say that based on DATA, there is no performance gains and probably no appreciable economy gains for premium.

 

[BigPainRing]

I use Costco 87.

I like Woodford Reserve 90.4. My car likes any brand 87.

 

[CX-SV]

"We also spoke to Mazda engineer Masuhiro Mora, who told us that although the American CX-5 is tuned to run right as rain on 87 octane, there's likely to be at least a modest performance benefit to filling it up with 91 when we eventually test it. "With 91, you should have slightly better torque in theory," he said."

I'm going to believe engineers at Mazda that actually finished the job and specified regular gasoline in the Mazda CX-5 owners manual. I will be running 87, until Mr Mora gets off duff (not likely).

It's nearly 2 years, no followup, so it was just empty talking.