I was recently told at a dealership that I should stop using premium fuel on my F-150. Besides saving money they told me that premium fuel on a vehicle that only requires regular does more harm than good. They told me that premium fuel burns at a higher temperature therefore leaving more carbon deposits. I just want to know if this is true or false.

 

The recommended fuel is regular 87 octane, so why use premium? More cost same power...

 

what about where regular is 85? use mid grade?

 

By using premium since it burns slower, you could be getting less output than running 87 octane. You need higher compression to actually utilize the slow burn effect.
Higher octane contains more MTBEs as per the regulatory commission in 1979 to rid fuels of lead. The higher concentrations of MTBE will have a carboning effect as a byproduct of it's burning. I have been running 87 for more then a year now on my 5.4 and can say it performs fine, even when towing.
Stop throwing your money to the oil companies!

 

That's because a service writer told you this probably. Service writers are the bottom of the knowledge chain at a dealer.

The difference between regular and premium is the tendency to pre-ignite under compression.

If you aren't knocking with regular you don't have to use premium.

 

These engines are designed to run properly on 87 octane. Light pinging, under load, is normal and nothing to worry about. We have seen drivability issues when people regularly use higher than 89 octane. You might occassionally have to put in 89 if the pinging is louder than you like, but anything higher in octane in a new ('96-up) vehicle is a complete waste of your money.

 

personally i use reg unleaeded except for probably every 8th or 9th fill up then i put a tank of midgrade in truck seems to enjoy that lil octane boost

 

If it's not predetonating the truck doesn't know 87 form 89!

 

Putting in a tank of midgrade every 8th or 9th tank is useless and the truck can't "enjoy" an octane boost. The BTU content of all grades of gasoline is exactly the same. Higher octane makes fuel burn slower...that's it!

Amazing how much oil company advertising affects some people's decisions!

 

The person who told you this about not using premium for money savings reasons is 100% correct. Using fuel with an octane higher than the minimum of what the car was designed for provides no benefits. Zero – none – natta! In fact, there are times of the year when you can safely operate your vehicle with less octane than the minimum.

As for carbon deposits, . . . I too have heard this and believe their is some validity to it, . . . but can not find reference material to back that claim up. BTW - some sports cars (like my BMW with a high compression engines) do require higher octane fuel. Here is a link that goes into way too much information on octane and engine performance, . . . but is nice to know.


Octane Discussion

 

Shouldn't the computer take care of any pinging in these motors?

 

Yup, every engine has a knock sensor which will signal the ECU to adjust accordingly. The basic map in the computer is written for 87 octane, therefore even at the timing limits you can still use 87. That's why a lot of the tuner modules you buy that plug into the service port, they remap the ECU to advance the spark more along with other things which then requires you to use premium fuel in the so called performance mode.