i use costco gas exclusively with no issues.

quote:

Check your gas cap, especially since this seems to happen after filling up. If it’s loose or worn and not sealing properly can cause the ck eng light to come on

A unsecured (or in many cases a faulty cap) is indicted by a separate warning light. Had the issue with a early Ford capless system.

The mechanic mentioned the gas cap and checked it , while in the shop.
He said it's fine ,just fine,
but I will be sure to check it in the future ,
if we get back to costco

Ethanol-free gas is becoming more readily available in many areas. It may take some effort to find it.

It is imperative to only use ethanol-free in small engines like mowers, weed whackers, chainsaws, and such.

Any older vehicles and engines with fuel systems and carburetors that have metals or rubber and other components that are susceptible to damage from either alcohol softening, or the damage from water being absorbed by the alcohol.

(Ethanol absorbs water, but it also helps keep water in a solution. When the Ethanol evaporates or other chemical/physical conditions occur that liberates the water, and it collects at the bottom of the tank and then picked up into the supply, it can result in the intermittent rough running.)


The other issues are evaporation of the alcohol and the residual fuel being "gummed" up and causing damage to components, or issues with operation.

A lot of the ethanol fuels if left to sit in carbs, lines and smaller tanks can become gelatinous and effectively prevent the starting or running of smaller engines.

In older vehicles, the rubber fuel lines, and other components of carburetors, fuel pump diaphragms and such can become soft, swell or even decompose and create blockages, as well as the "evaporation" of the alcohol, leaving water and "bad" gas (hard to burn).

But, older autos with updated fuel lines, Fuel Injection systems, and other modifications can benefit from both E-10 and E-85 blends by reducing detonation and running cleaner than non-ethanol fuels. (Many folks in the drag racing world use ethanol blends in high compression engines to reduce ping without having to tune and pay the higher price of leaded fuels or other "race gas" options.

One just needs to read up and understand the differences. It is not simply an "ethanol good/ethanol bad" argument.

Mixing is fine, as long as the understanding of what the mixing does or does not for the specific application with regard to the engine, fuel system, and components that may or may not be affected.

Ethanol blends do provide less power to quantity ratio, of up to a third less than non-ethanol blended fuels.

I have a Ford Fiesta ST which features a small high output turbo 4 cylinder, to the tune of 197 HP on premium fuel. Those driving cars like this will often purchase a "tune" to boost their horsepower. in Some casea a simple change to the computer can result in 40 HP or even more if the fuel has a high enough octane. Alcohol is an excellent way to boost the effective octane in a fuel mix, because it not only increases the chemical octane it also cools the intake charge that provides a further increase in the Effective Octane. One of he most popular tunes is an E30, as in 30% ethanol. It provides an increase in HP and Torque but is conservative enough to greatly reduce the risk of engine damage. Note, the Fiesta ST is NOT E85 compatible. Point is that a bit of alcohol in our fuel isn't anything to worry about in a newer care, even an oldie like my 1985 Monte Carlos SS which has been running 5 to 10% blends for over 30 years.

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and all three times , within about 100 miles ( four or five days) I noticed either a slight rough idle at start up, or the check engine light would come on.

It's not from a mere 10% ethanol. Any car/engine made since the 1980s is made for and runs fine on it. In any event, all you're doing with the 100% gas is diluting the already small amount of ethanol, so mixing is fine.

I can only recall one time a car had a problem with outright faulty (water-laden) gas fresh from the pump, as opposed to sitting for years and turning to syrup, leaving the gas cap off and getting rained in, etc. That gas was so bad that it didn't even have the usual strong odor. I could draw some off, sprinkle it on the floor, light it, and it would barely burn for a few seconds and go out. Could you get such gas, yes, but it's very rare.

Thanks to those choosing to take the time, It is appreciated.

Two years ago ,When I purchased this car , I got 20 m.p.g. for 13 months , then on a trip to Indiana it started to get 23 m.p.g. ( woo hoo) .

It consistently gets right at 22 m.p.g. , combined .