recommended grade of gasoline

The manual recommends 87 octane or higher. I would go with what Honda recommends not what a dealer employee says. Also says up to 15% ethanol is ok, but I avoid ethanol gas since my gas sits in the tank for a long time and I want to avoid potential problems with moisture and condensation.
Page 451
Edited to respond to @ClarityDoc:
The manual doesn’t actually recommend regular gas; it just says 87 octane or higher. But for most of us that is the lower regular grade.

 

^^^ This

I have started using non-ethanol gas for several reasons...moisture, overall engine health (debatable) and increased mpg. I just put in the second tank of non-ethanol so still in the process of determining increased mpg which is evident but percent increase TBD down the road.

For complete info...in my area...non-ethanol is only offered in 89 and 93 octane...which translates to premium $$$ per gallon.

As KentuckyKen said...the worlds your oyster.

Good luck.

 

Honda recommends regular and does not warn against ethanol. Great thing about the Clarity - it doesn't need to be complicated unless you want it to be.

Sent using Inside EVs mobile app

 

What many fail to mention, or understand, is that terminology is everything. For example original poster says the dealer recommended "the highest grade" gasoline. And responses so far has varied from interpreting "highest grade" meaning "highest octane", or "lowest ethanol", or whatever.

The specific words Honda actually uses is that you should use TOP TIER DETERGENT GASOLINE. This may be what the dealership said to O.P., and was lost in translation. Top Tier is a branding thing which has absolutely nothing to do with octane, or ethanol. Truth is Honda specifically states there is no sense in using higher octane than the manual calls for. They also recommend you should purchase your gasoline only from retailers on this list:
https://www.toptiergas.com/licensed-brands/

As for ethanol Honda addresses this very clearly too: Direct from page 451 of our Clarity owner's manual: "Some gasoline today is blended with oxygenates such as ethanol. Your vehicle is designed to operate on oxygenated gasoline containing up to 15% ethanol by volume."

As for fear of moisture or whatever in the tank? The Clarity has a very unique pressurized fuel system. No moisture can possibly get in there, so it's a non-issue to be concerned with.

Summary: Honda's recommended fuel is very clearly stated: 87 octane, 15% ethanol or less, and sold by a Top Tier retailer.

 

While I agree that the pressurized fuel tank is a big help for keeping the fuel fresh, I would have to disagree that “no moisture can possibly get in there”.
One, every time you fuel up you open the tank slightly to ambient humidity and two, ethanol is hygroscopic (loves or absorbs water) and any ethanol blended fuel will necessarily have some small amount of moisture. And the pressurized fuel tank cannot remove this moisture. This is why I avoid ethanol blends like the plague.

 

I use cheapest gas at individual station. Usually that is 87 with 10% ethanol. Ethanol contains about 30% less btu/gal energy, so 10% ethanol has only about 3% less energy than pure gas, so as long as it is 3% cheaper it makes sense to buy it. Since it is usually 10 or 20% cheaper locally I see no reason to buy anything else.

Ethanol had issues early because of a no longer used additive MTBE, when mixed with ethanol it could cause gelling. Since MTBE is rare these days there is no issue using ethanol in any car made in the last 30 years or so.

Any car 2002 or newer can safely use 15% ethanol blend. Older cars should not use 15%. Almost all fuel sold in the US contains some ethanol (it replaced MTBE), some states don't even have to indicate it is there, others only if above a certain percent (like 1 or 2% range).

 

Agreed that the moisture issue concerns the entire supply chain, not just what's in the tank once the cap is put back on. Having said that, I also have no idea of the scale of any moisture problem and what, if anything, it does But, having said that, my local station sells ethanol free top tier premium for 0.30 cents more than regular, which does have up to 15% ethanol. For better MPG and to eliminate alcohol/moisture problems, I use premium. It's cost me only $4.50 for doing that for the entire time I've owned the car. And I'm sure I've been getting 0.000001 better mpg.

 

Indeed. It's hygroscopic. And I'll concede a few molecules of water can get in. And that ethanol holds that minute amount of moisture in suspension because of its hygroscopic properties, and burns it off harmlessly. I've burned E-10 in everything I own...and it's run in everything I maintain for customers...and have done so for the better part of 2 to 3 decades because that's all that is available here in Indiana without spending and extra $1 or more per gallon at a specialty place. I know how to modify and rebuild Rochester, Carter, and Holley carburetors and fuel systems for classic muscle cars so they run properly and trouble-free on today's E-10. I park my modern snowmobiles (used 2 months, then parked 10 months), with ethanol fuel in the tanks all summer long. I assure you I fully understand the fuel, it's long term storage challenges, and it's shortcomings. And much is incredibly overblown, exaggerated, and misunderstood on the internet.

Older vehicles with the wrong plastics and materials in the fuel systems, atmospherically vented fuel systems, many small engines with cheap fuel system parts, and a multitude of machines indeed can suffer from ethanol related fuel problems. 90% is due to improper storage. I will never deny this. I have seen and repaired the corrosion it can cause, cleared systems of phase-separated fuel, etc...it happens.

But not in modern cars. They simply do not have these problems anymore. In fact it is actually cleansing. As long as water isn't there, the fuel systems of vehicles run with ethanol always look less varnished than those running pure gasoline -- the ethanol cleans systems incredibly well. I have fixed a lot of fuel system problems on many vehicles in my career. And I can confidently say I can't recall a single ethanol-induced fuel problem in a fuel injected car that was built in this particular century, unless that car sat completely unused for maybe 2 years plus. So if your plan is to use no fuel for the next 2 years, YES, get the ethanol out of there as it will cause some problems.

But I will maintain for anyone that it is 100% harmless for the Clarity, as long as you burn off about 10 gallons per year so it doesn't get TOO old. Honda agrees it's fine up to 15% concentration and says so right in the manual. As always, individuals will do their own thing, and running non-ethanol won't hurt anything but the pocketbook either, if that's what some choose to do.

 

craze1cars

"...Truth is Honda specifically states there is no sense in using higher octane than the manual calls for..."

Speaking for myself, pure gas is the key...not octane. I mention octane only for full disclosure and the fact higher octane, pure gas is pretty expensive. I think you got hung up on the octane when pure gas is what you should have honed in on.

Pure gas burns more efficient then diluted gas. Plain and simple. Whether or not it makes a noticeable difference in the Clarity mpg or longer term engine health is still TBD...IMHO.

I've read your previous posts about moisture is not a problem with the Clarity gas tank and plumbing. It is information I retain for future reference and understand what you are saying and respect your obvious knowledge.

IMHO, give this vehicle 3 years or more in the real world...then one can quantify the moisture question. Until then...anyone's guess. The real world has a way of ferreting out such claims one way or the other.

If an owner decides to run 87/15 gas...great, more power to them. If they want to run pure gas...great, more power to them. No harm, no foul.

Have a good day.

 

As a note about water contamination of ethanol, water will contaminate gasoline just as easily and can cause running problems. Since ethanol attracts water it is actually useful for removing water from the fuel system. It could get phase separation, under storage but only if vented to the atmosphere, which it is not in the Clarity. The only time it could have this is upstream, but they have means of dealing with it at stations.

Phase separation is more likely at lower % ethanol, so it is actually more likely to get phase separation in your 1% ethanol non ethanol fuel than your 10% ethanol fuel.

Something like 95% of fuels in the US contain ethanol.

 

And on a positive note...
The Clarity must be a fantastic car if ethanol in the gas is all we have to nitpick over. I really appreciate everyone’s combined knowledge and experience shared here. I always learn a lot from this forum. So to all you who I will never meet; thank you!

 

Agree entirely. 100% Ethanol is 33% less efficient than 100% gasoline. This means there is almost exactly a 3% loss of power and fuel economy when comparing E-10 to pure gasoline.

I use this math frequently when rejetting and drilling out passages on those old muscle car carbs...it burns leaner and therefore the engines on those cars require larger fuel flow to maintain correct air-fuel ratio on E-10 vs the pure gasoline they were designed to run on. Fuel injected cars do this adjustment automatically with computers on-the-fly, but the 3% loss is still there.

And I'll throw out a point of irrelevant trivia -- Indycars run on 100% pure ethanol with no gasoline. They just cram 33% more of it thru the fuel injectors to get the power out of them.

Good to mention.

 

100% accurate.

On a semi-related note, this is why "Heet" exists in northern climates. In the days before ethanol mixes, you'd buy this stuff by the case and dump it in your fuel tank with every fill up in the winter, in order to introduce the alcohol with the GOAL of making your fuel hygroscopic. Because if you didn't, and you had a drop of water in your fuel, it would sneak into your fuel line unabsorbed, freeze into a crystal and clog somewhere in your fuel line and shut you down until you were able to warm the car up somewhere. The best fix for this was a few hours in a heated garage, or a warm day...then it would fire up like nothing was ever wrong and the melted water crystal would pass thru.

Now if you run E-10, the Heet thing is largely obsolete -- cuz it's built into the fuel at the pump. And freezing gas lines are never a concern with an ethanol blended fuel.

E-10 is known to wreak havoc on boats that live docked in slips all year -- high humidity everywhere, water everywhere, lack of use/long term storage is typical for most boats -- fuel sold at marinas is almost always ethanol-free for these reasons, and rightly so.

 

Indycars run E85 (85% ethanol, 15% gasoline). One reason is advertising for ethanol as the midwest is a major producer of corn for ethanol. The main reason is that pure ethanol burns with a flame that is hard to see, especially in daylight. Adding some gasoline to the fuel makes for more visible fuel fires. E85 will continue to be used in Indycar for at least the next couple of years:

https://racer.com/2018/12/07/indycar-to-stay-with-e85-fuel-through-2020/

LeoP

 

After all these informative posts, I now confess total ignorance on the ethanol issue with the one exception that I can boldly say I prefer my ethanol in my glass and not in my tank.

 

My mistake! Thanks for the correction....it was near 100% in the mid 2000’s but indeed it seems it was reduced to E85 in 2012 and has stayed there since...

 

Wow! only $0.30 more per gallon than regular? As I recall, it used to cost about $0.75-$1 more a gallon at the local station, and that wasn't even top-tier.

 

It’s amazing how across all vehicle forums the way to ignite postings and bring out an almost religious fervor related to car care is to ask either “Which gas should I use?” or “Which oil should I use?” In this thread we already have 18 posts on something that’s right in the Owner’s Guide, page 118. That’s cool; I already learned something (Indy cars use E85!).

 

Agreed. Amazing the things you learn here that have nothing to do with the Clarity.

I did a little research when this thread appeared and found two flavors of information on the topic (ethanol in gas). It's either the greatest thing ever, or evil incarnate!