Flex Fuel

Off topic but a friend of ours just topped off her Mazda 6 GT Turbo with flex fuel by mistake. What should she do? Check engine light has already come on I'm assuming due to the O2 sensor.

 

Have it towed to a garage and have them drain the fuel system, flush the fuel lines and replace any fuel filters. This is the only option that will not cause damage.

 

Depends how much she put in, if it was only a few gallons it should be fine just fill it with regular after it's down a bit. If it was a lot it would be a good idea to pump it out and put regular back in it.

Almost all gasoline sold in the US has at least 10% ethanol so fuel systems are designed to tolerate it, the main difference between a flex fuel and non flex fuel vehicle is flex fuel vehicles have programming built in to change fuel strategies based on fuel composition since ethanol burns differently than straight gasoline.
Non flex fuel vehicles are not programmed to handle running ethanol and will not run correctly on anything more than about 20%

 

Yea she filled it from empty. The stealership is going to hit her up for $150 to drain the tank. Thanks for the tips guys!

 

At least it wasn't gasoline or DEF put in a diesel, that could potentially be a $10,000+ mistake.
Lessons learned

 

Had the self proclaimed genius at work do that a few months ago in the 2020 F250 super duty. It was right at 13k

 

IMO it's worth the money they want to drain the tank. Then the problem is gone before the computer goes even more biserk and starts throwing more codes to clear. A good chunk of that charge will probably the fee for disposing of the E85. Think of it this way: at current prices of unleaded, it would likely cost at least a C-note to fill the tank. A fill-up from 1/2 on my truck is easily $50-60 currently. 1/4 to fill-up is an easy $30.

 

I'm not an expert here this information may be incorrect. I remember something about rubber swelling in the presence on concentrated ethanol. Fuel systems that can higher concentrations of ethanol, don't use rubber seals. Again, this information may be wrong.