Scott, Ford recommends 87
Scott, Ford recommends 87 octane in all FEH/MMH models. I've put Premium in my tank by accident and got at least a 3mpg reduction on the tank. Premium fuel burns slower and is needed in higher compression engines to prevent pre-ignition. For the best mileage in the FEH/MMH, use straight 87 octane without ethanol if you can find it. E-10 (10% ethanol) will reduce our mileage up to 15%.
Everything seems to
Everything seems to be E-10 here... I was getting less mpg before the synthetic oil change and tire inflation and have been using premium since. Will try a tank of Unleaded 87 next tank... is it possible that the premium has less E10 content?
Scott, I would say E-10 is
Scott, I would say E-10 is your problem with gas mileage for sure. If there was a way to filter ethanol out of the gas, I would myself. Check the marinas to find out if you can get straight 87 octane from them because most AV gas is higher octane. E-10 screws up outboard motor carbs and other small engines like lawn tools that mix oil with gas. The ethanol creates a sludge when mixed with oil gas mixtures so maybe the marinas get straight gas. I would go so far as to pump the gas in cans at the marinas to fill my boat, small tools and my FEH's. In fact, I going to go to a few marinas to see if I can get gas without ethanol from them here in Florida where E-10 is mandated at all gas stations since June of this year.
Also, it will take up to three tanks of straight gas for the PCM to adjust the long term fuel maps in the Keep Alive Memory (KAM) in your FEH. You can reset KAM to the default settings by disconnecting the ground on the 12V battery for a least 5 minutes. If you burn all the E-10 out, I would reset the KAM and add straight gas to speed up adjusting the long term fuel maps in KAM. Once the maps are adjusted to straight gas, don't use any more E-10 or you will be back in the same boat as you are now. E-10 has an instant effect on mileage as soon as it runs in your engine. Trust me, I have a lot of experience with E-10 prior to the mandate in June because some stations like Citgo was pumping it here long before the mandate. I knew I filled with E-10 two miles from the station because of the huge drop in mileage in my FEH.