[714BMW]

Going to be going out of the country for 7 days early next month. Car has been running full e85 for 6 months straight and ongoing. Is it alright to let the car sit for a week without any movement with the full E in the tank?

Thanks

[thejeremyman9]

Yes, 7 days is nothing. 1 month or more i might think about it. As another data point i leave E85 in my 3000gt for months on end and i only drive it roughly once a month and refuel every 3 months. And that is on fuel system components from 1991 most of which are not ethanol rated like modern cars

[714BMW]

Originally Posted by thejeremyman9

Yes, 7 days is nothing. 1 month or more i might think about it. As another data point i leave E85 in my 3000gt for months on end and i only drive it roughly once a month and refuel every 3 months. And that is on fuel system components from 1991 most of which are not ethanol rated like modern cars

Understood. I appreciate the response! Vacation mode soon

[435gc]

My understanding related to the corrosiveness of ethanol is that the the issue is due to the ethanol's pull of water into the system. The more water pulled in, the more the more corrosive the mixture becomes.

If I were to leave a high concentration of ethanol in the gas tank for a prolonged period, I would probably want to run that tank through quicker and refill sooner to remove whatever water has accumulated.

[thejeremyman9]

Originally Posted by 435gc

My understanding related to the corrosiveness of ethanol is that the the issue is due to the ethanol's pull of water into the system. The more water pulled in, the more the more corrosive the mixture becomes.

If I were to leave a high concentration of ethanol in the gas tank for a prolonged period, I would probably want to run that tank through quicker and refill sooner to remove whatever water has accumulated.

Correct in that ethanol is hydroscopic so it absorbs water vapor from the air. The other issue (mostly on older cars) is that ethanol eats through older rubbers that were not made to be compliant with ethanol, especially in higher concentrations in gasoline.

[435gc]

Any idea what year newer rubber that is less susceptible became standard?

[thejeremyman9]

Originally Posted by 435gc

Any idea what year newer rubber that is less susceptible became standard?

Not sure exactly but based on the fact that 10% ethanol blends started in around 2005 i would say around then

[johnung]

Originally Posted by 435gc

My understanding related to the corrosiveness of ethanol is that the the issue is due to the ethanol's pull of water into the system. The more water pulled in, the more the more corrosive the mixture becomes.

If I were to leave a high concentration of ethanol in the gas tank for a prolonged period, I would probably want to run that tank through quicker and refill sooner to remove whatever water has accumulated.

Growing up I recall being told to keep the gas tank full in the winter. The added weight provided traction. But having a full tank also lessened water accumulation in the tank.

Water in fuel comes from the air. A big tank with a few gallons in it has a lot of air with moisture in it. A full gas tank has little air so it has less potential water that could get into the fuel.

[johnung]

Originally Posted by 714BMW

Going to be going out of the country for 7 days early next month. Car has been running full e85 for 6 months straight and ongoing. Is it alright to let the car sit for a week without any movement with the full E in the tank?

Thanks

A week is no problem to sit with E85 in the tank. But it's often recommended to run a tank of gasoline sometimes for the added lubrication of gas vs ethanol. If your on a FlexFuel tune why not run the tank down and fill with 93 before you leave on your trip?