Fuel Type - Ethanol's effect on MPG

Apologies... Had I known you read the owners manual and were interested in more thoughts/details about Octane for Prius I'd of engaged in the conversation much differently... I overreacted because too often new people don't exhaust the most obvious available resources to them before asking.

Part of the problem is that in order to search this forum for answers you have to realize that search boxes for most website forums never work as well as search via Bing or Google.... So for example if you want to know more about Octane discusisons you enter into a Google search engine the following text:

site:htp://priuschat.com octane

(note: I left a 't' out of http so the forum software doesn't convert it into a link)

When you do this you'll get loads of links, especially the most popular links, rather than a confusing list via the website's search box, which isn't optimized as well. For example I just tried this for PriusChat search vs. Google search and got much different results.

Here are results for this website's search function: Search Results for Query: octane | PriusChat

vs.

Here are results via Google's search of this site: Google

Another reason my answer was a bit smug is that I've been on this site for 6 months and I love it and I've never had to start a new post/thread to get an answer to a question. There is a huge amount of information, most of it redundant and the quality of the experience gets diffused when new people start a new post rather than make their comments in the threads of the many existing posts. But fact is everytime you post to an existing thread everyone who has commented on that existing thread gets word about your post/question so it really is the fastest way to get an expert response....

And yes I do have a couple unanswered questions that I'll someday formally post, but for now I'm still exhausting all my options before I ask...

And yes, I really do mean welcome to PriusChat... And apologies again for my tone. The internet is limited because words can be taken the wrong way when you can't see body language and facial expressions that go with it... The whole point of my post was done in fun, not intended to offend.

 

Apology accepted - let's be friends I agree, the internet and/or forums are limited by the actual words typed, lacking the tones and inflection of spoken word. I think I may have jumped the gun a bit with bashing you, sorry for that.

That is a *FANTASTIC* tip which I will put to good use, not only for PriusChat but for other wedding photography forums I am a member of, too. Thanks for that!

 

No problem... And apologies for thinking you were starting a new post, that was my bad... I didn't check my alert to your post closely enough...

 

I agree with that. If some of the people would read the entire thread, a lot of the questions would be negated. IMO technology has taught us to search for answers by typing it into a search bar rather than read, so people will generally ask already answered questions. At least though people have questions to ask and are curious. Instant information is a blessing and a curse IMO. And to MandyTee, Welcome! (I am a bit envious of your owning a Prius C, will get one eventually )

 

LOL at your reply.

Someone here did a comparison of 87 octane and something higher, probably a couple of years ago. You might be able to find it with a search, but the search function isn't the friendliest. From what I recall with my fading memory, there was a very slight improvement in fuel economy but not enough to justify the extra fuel cost.

A reason for getting better fuel economy with higher octane fuel could be that the engine doesn't have to pull back the spark advance as often with the higher octane. How much difference would depend on the car, the fuel and operating conditions. If you were to monitor the OBD-II data stream you could record how much spark advance is pulled out with both fuels under different conditions.

 

Just to note, you can actually leave out the htp:// too -

Code:

site:priuschat.com

will do the trick.

For what it's worth, down here Toyota actually specifies RON 91 for the c and RON 95 for the liftback. Sorry, I'm not sure how to convert the RON numbers to US octane ratings.

 

The US-Canada-Mexico Octane rating is (MON + RON)/2 so you can't do an accurate conversion with out also knowing knowing the MON number for the your gasoline. That said, if you subtract 4 or 5 from the RON number you will be close enough to the US-Canada-Mexico Octane rating for a rough approximation. The problem is that a few gasolines can be as far as 7 or maybe even a bit more points different.

The US-Canada-Mexico rating system is a better relative indication of how the fuel will behave in a real car, so maybe Toyota was being cautions when the called for RON 95 for the liftback 95-7= 88).

 

Okay, based on that I did a bit of Googling with a touch of local knowledge and came to Fuel Quality in Australia - Petrol Fuel Quality Standard

This sets our "regular unleaded" at a minimum of 91 RON / 81 MON and "premium unleaded" at a minimum of 95 RON / 85 MON, which if correct would convert using your formula to 86 and 90 respectively.

E10 fuels here only have to meet the minimum standard but different companies have chosen different approaches - currently I can and do avoid them.

 

you can also just do for example: "priuschat.com octane"

But each one will have slightly different results...

Main point is doing a decent google search has everything to do with using more than one set of search terms...

 

Another bad thing about Ethanol... It's a breeding ground for Fungus!!!

Kentucky town taken over by Whiskey Fungus http://nyti.ms/PuNVfa

 

Hi Rob hope all is well, can I ask why you say your last sentence ? "currently I can and do avoid them" has your stance changed on this at all, currently here in Victoria petrol prices have gone mental $1.65 a litre so it makes the E10 at $1.60 look a bit more attractive

 

In NSW, E10 is normally 2¢/litre cheaper than U91. The higher the price goes, the smaller the % saving at the pump becomes, making E10 even worse value than it already was. 158.8¢/l is only 1.25% less than 160.9¢/l.

Aside from my other concerns (that all the arguments for Ethanol are provided by the industry and aren't backed by multiple peer-reviewed scientific studies that are not sponsored by industry), currently it's just flat-out poor value.

 

ChE handbook lists heat of combustion for ethanol 12.800 btu per pound while gasoline is 20,200 btu per pound so you csn see ethanol will decrease your mpg by its presence. Worse, ethanol is very corrosive and attacks many liquid seals etc.

 

CorrectE10 at 12.8 X .10 + 20.2 X .90 = 19.46 or 3.6% less energy than pure gas (assuming either your . or your , was an error)

 

I m newbie to this Prius C baby n I came across this topic to show my husband that my Prius C baby only need 87 regular gas but he objected the ideal of putting regular gas into prius C. He insists I must put Super because Super is more "clean" gas than Regular n it can prolong your engine life .....Is this correct?

Also to all Pro PriusC owners, what is the best app (for Iphone) you use to keep track of the fuel mileage?

 

To my knowledge there is no information to suggest Premium is cleaner (these days EPA regs control a lot more and probably regular grades are cleaner than yesteryear). There is a need for detergent additives in all grades of gasoline to help keep engines clean. If you are concerned about this you might want to stick with TopTierGas.com which lists name brands which commit to higher levels of additives. Most Prius drviers are trying to maximize fuels savings, which generally involves buying the 87 Octane grade Prius is designed for. I am under the impression that the chemistry causes for sludge build-up are complex and not well understood, so the additive approach is the general approach.

 

It's one of those urban legends. It won't hurt the engine and "might" run cleaner due to the additives, but it will be more expensive for a "might"

 

I hate pee in anybody's potted palm plant, but a fifteen percent MPG delta isn't going to be caused solely by putting alky-haul in the fuel. "My" Prius isn't really MY Prius. It's a company car, and so my choices in gas stations have more to do with things like restroom cleanliness and Gedunk selection than by the big red numbers on the sign outside. However (comma!) like many new Prius drivers, I did tinker with things like E0 versus E10, tire inflation, P-n-G, and a few other things.
Despite the fact that I did (and still do) assiduously track my mileages I never really saw the 3-percent delta that the MPG geeks said that I should have seen by running several tanks of E0.
The really funny thing is that the seedier mom and pop stations in my area have big signs proclaiming their product as "REAL GAS!!!" which proves what P.T Barnum said a while back about suckers since in this area..."real" gas is about 10-20 cents more expensive than E10. I'm waiting for the bigs to latch on to this idea, but for now they still have the suckers that put higher octane fuel into their cars because they love their cars more than I love my cars.

There is a saying in the Canoe Club.
RTFM, which (almost) stands for "Read The Factory Manual" but when I drove a podium for a living we also used to say that the only stupid question is the one that you DONT ask.