So I did something stupid, I guess.
I have a 2014 Mustang GT and it has one of the gas caps were there is no gas cap. You just open lid and insert nozzle.

1. I tried adding a fuel additive to help maintain/clean my gas system. I poured a little in and it went down. Poured a little more, still went down. When I was finished - all of the fuel additive was on the ground under my car. How are you suppose to add a fuel additive to cars with these different fuel safety things?

2. Is it bad to go from 87 Octane to 93? I'm sure it is bad to keep switching back and forth but is there anything I need to do to start using fuel with a higher Octane?

 

1. Go in the trunk and pull up the carpet. If you're looking where the spare would be, there is a white plastic funnel on the right hand side of the spare, towards the rear of the car. It is slid into the spare area so you will only see the top part. This is what you need to use to add anything to the fuel tank.

2. I'm no expert on the specifics but I know our cars are "meant" to run on 93 octane.
I think the first rule is to not switch back and forth so if it's inconvienent for you to find 93 or are not prepared for it financially, I'd say stick with 87. Otherwise, when you fill up next time just do 93 and then continue that. I do know our Coyote's will pick up the difference automatically and you'll make more hp.

I'm sure there is a link with much better info somewhere but I never cared about the specifics myself - I always run 93.

 

Thank you for the replies.
I was unaware of this funnel...

 

This is of dubious value on old cars with lots of miles. For a 2014 Mustang, there's nothing dubious at all. No value whatsoever.

 

I thought that too. Unlike many people that own Mustangs though, I drive my Mustang a lot. I put about 20k miles per year on mine. So I figured why not?

I've see a lot of people with their Mustangs for years with barely ANY miles. After a good laugh, I agree- I wouldn't bother with dumb maintenance like a fuel additives then.

 

I agree that most gasoline additives are snake oil, but I think there are a couple of exceptions.

If you're not using top quality gas (probably no one here, lol), then an occasional bottle of Techron can remove deposits.

I like to add a bottle of Iso-HEET a few times a year to remove any water that may have collected in my car's gas tank.

 

I typically add Techron about every 10k miles as preventive maintenance. It doesn't hurt anything. As far as octane, no, it wont hurt anything but the added RWHP is minor unless youre tuned for it. And, as an example, putting 8 gallons of 93 octane into a tank with 8 gallons of 87 octane gives you a tank of about 90 octane so unless the tank is close to bone dry, you'll be somewhere between octanes unless you do consecutive fillups of the same octane.

 

there's no such rule. The engine and PCM don't "know" what octane rating the gas is. The only thing it does is will retard ignition timing (and maybe slightly enrich the mix) if the knock sensor(s) indicate pre-ignition or detonation. If you're not pinging when running 87, then the car literally has no idea whether you're using 87 or 93.

 

The only additive worth buying is Techron. For your Mustang, make sure you get the 20 oz. bottle. The others are primarily kerosene.

 

I guess it's a personal rule

Owners manual says "Premium fuel will provide improved performance". Tons of info out there about +10-15hp for 91/93 over 87. I didn't get citations because again - I run 93. Also I don't care to argue over it as you sound more educated than I and the OP can do his own research if he cares.