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Why are some gasolines not as clear as others? Is this an issue?

I recently drove the 30 miles to the closest gas station to me that sells ethanol free fuel. Its a countrymark station and their 91 octane at some locations is ethanol free. I filled up my Prius with the ethanol free fuel because I was there, and I got 15 gallons for some of my yard equipment as well.

I noticed something odd though, when I filled up my mantis 4 cycle tiller, which is new so the fuel tank is still really clear, I found that the 91 octane ethanol free fuel was darker than the fuel I had been using.

I poured the two different fuels I had in clear glasses and I found that the 91 octane ethanol free fuel was slightly darker than the 87 octane 10% ethanol fuel that I normally use.

Why is this? Wouldn’t clear fuel cause less deposits than fuel that is not perfectly clear? Im curious. Wouldn’t clear gasoline be gasoline that is refined more?

I must also note that the ethanol free fuel smells differently. Its been so long since I smelled real gasoline im not sure what gas is supposed to smell like.

You don’t mean cloudy, right, just a darker tint? That’s no problem, just a result of a different mix of chemicals in the gas. There are lots of additives for cleaning, etc, any one of which might have a different tint. And yes, E10 will smell different than E0. One reason is the other chemicals that come along with the ethanol in E10.

Unlike vodka, ‘clear’ doesn’t mean ‘pure’ as far as gasoline goes…

You don't mean cloudy, right, just a darker tint?

Yes, just a darker tint, not like it has water in it or anything. I have been using the E0 Gas and have noticed no difference in performance, bad or good. I feel the gasoline is of good quality, just darker than the E10.

I suspect the “ethanol free” fuel is actually avgas or marine grade gasoline, both of which will be dyed a slightly different color for identification…Most “regular unleaded” is a pale green color and premium is a light pink color…Mid-grade, which is just regular and premium blended 50-50 results in a orange color…

Did you pay a considerably more than normal for this gasoline?


Did you pay a considerably more than normal for this gasoline?

No, I think I paid 4.01 a gallon for it, and at the time premium at other stations was within 10 cents of what I paid. There is a countymark in the town I live by but they do not carry ethanol free fuel, only some of those stations do.

Many of the stations that have E0 in Indiana are either at an airport or marina, however the station I got the E0 from is not.

What you purchased is probably 100LL avgas before the lead was added…

It looks like, in the future, new light propeller driven aircraft will be powered by a new line of Diesel engines…The availability of “avgas” is becoming more and more uncertain…

Fuels are dyed to identify them. For example, “off road” diesel fuel is dyed red to indicate it hasn’t been taxed and it can only be legally used in applications that are exempt from highway fuel tax. Farm tractors, generators, construction equipment, etc.

from “”:

What gives gasoline color? Many different things. Some bad, like PNAs (polynuclear aromatics) mentioned by Tracy, some not so bad. A lot of companies add anti-oxidants to keep down gum formation and that also helps color. However, a lot of gas stations are re-filled daily, so storage time isn't a problem. Premium is generally less colored due to how it's made (little or no PNAs, etc). Regular and midgrade are made from many things and generally have some color. I'd be concerned with any gas that was bright yellow or premium that was anything other than white or faintly yellow.

Yeah dye was what I was thinking. Common for diesel that tax has been paid on versus non-taxed like for farm use. Maybe they are trying to be able to determine if you are using boating gas for road use or something. Nothing I would worry about though.

Avgas is dyed to prevent fueling mishaps. You don’t want to put the wrong gas in your airplane.

•100LL – Blue
•82UL – Purple
•Avgas 80/87 – Red
•Avgas 100/130 – Green

B.L.E. Absolutely to prevent fueling mishaps…AND when you sample the fuel, the tint helps make water contamination more obvious (blue fuel atop clear water).

In the days of leaded auto gas, regular used to be dyed yellow and premium used to be dyed red. My granddad used to buy unleaded and untaxed bulk gas for his tractor from the distributor. This gas, being totally un-dyed was commonly called white gas in those days. It was clear as water. It also had a very low octane rating but my granddad’s John Deere A had a compression ratio of around 4 to 1.