Happy new year to ya'll
I have a 2006 f150 fx4 with 106,000 miles. It's a 5.4 triton. I think it's one of the first ones that came out with the flex fuel. My question is do I stay with regular 87 or can use ethanol? Keep in mind that I've never put ethanol fuel in the system. Will it do anything my the engine? Where I live it's about 30 cents cheaper then regular 87. Thanks for reading.

 

You should be able to check in these places to make sure its a FFV..
1-There is a sticker on the fuel door or on the gas cap that says Flex Fuel Vehicle
2-The 8th letter of the VIN is a "V" as opposed to a "5" which means it's a Flex Fuel Vehicle
3-The emission control label under the hood reads "This Flex Fuel Vehicle Conforms..."

... But i wouldn't use E85 unless you like knowing your emitting less emissions and that's a big concern of yours..
or unless its at least about 40 cents cheaper, E85 gets much worse fuel economy, so the benefits of saving money don't really add up..I've heard its about 4-6 mpg less.

but yes if its not a FFV it can damage parts and obviously shouldn't be done.

 

If it is a FFV I would still stay away from it. I tried a few tanks in mine and the mileage was terrible. Given the other issues ethanol creates I only run the blends or occasionally I run ethanol free fuel when it's convenient. I definitely see an improvement in MPG when I run the ethanol free fuel. That's just my opinion on the matter.

 

In Illinois there is no such thing as "regular gas".. All of the gas contains 10% ethanol... then there is the E85 stuff... Having 10% ethanol in the gas constantly clean the injectors and system. I have been using it for 20 years and never had an injector or fuel problem. Original 1989 F250 went 250K miles, last 2001 F150 went 250K miles... both still running when sold.

 

If you have a choice where you live between gas and alcohol-enhanced gas, go with the straight gas. You can also use E10 without any special things done to the vehicle. However, you seem to be saying that you have a 'Flex-Fuel' truck which can run up to E85. If that is true, the choice is simply yours. I have to use E10 by law so I use Sta-Bil 360 which helps prevent fuel system corrosion from alcohol fuels and also cleans the fuel system with regular use. This has been going on for about 20 years now (I started using the red Sta-Bil and changed as they changed) and I've never had any fuel system trouble of any kind, and the catalytic converters stay sweet.
As an alternative, you could start using the E85 half and half and increase the ratio until you are using all E85. If anything was going to happen, maybe that way it wouldn't be a sudden surprise. But don't use anything higher than E10 unless you actually have a Flex-Fuel truck.

 

Even if you do have an E85 vehicle, the owner's manual advises to use regular fuel every third tank, IIRC.
As mentioned, the mileage is so poor there has to be a huge price difference to realize any actual savings.
You might want to run a tank through just to know how it runs, though...