First produced in 1999 and now in its fourth generation of production, the F250/350 is a member of the iconic Super Duty F series. During this article, we plan to look at the various engines used in the F250/350 and the manufacturer’s recommendation regarding which fuel to use and which not to use. We will then cap it all off by sharing the F250/350’s fuel capacity and mileage per gallon data.
Before presenting a detailed view, in the next paragraph, we first present a summary of all the engine types used in F250/350 and the recommended fuels types based on the manufacturer’s specifications.
The recommended fuel for gasoline engines (5.4L, 6.8L, 7.3L) used in the F250/350 is regular unleaded gasoline with a minimum octane rating of 87. Diesel engines are recommended to use Ultra Low Sulphur Diesel.
We will take a comprehensive look into which fuel to use based on the engine type in the following sections. Additionally, we will briefly analyze the popular fuel types available and their effect on engine performance, durability, and environment. Finally, we will present fuel economy and tank capacity data of F250/350 for each year of production and trim.
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Fuel Requirements Based On Engine Type
Let us now look in detail at the various engines used thus far in F250/350 and the recommended fuel as given in the manufacturer’s owner manual.
First-generation (1999-2007) and second-generation (2008-2010)
The two base gasoline engines used in the first and second generation are 5.4L V8 and 6.4L V10. The recommended fuel for gasoline engines is regular unleaded with an octane rating of 87. Ford also allows the use of clean air fuels, such as reformulated gasoline that contain oxygenates up to 10% ethanol or 15% MTBE (methyl tertiary-butyl ether).
F250/350 user manual states, “For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel is most noticeable in hot weather as well as other conditions, for example, when towing a trailer.”
The diesel engines used in the first two generations are 7.3L, 6.0L, and 6.4L, and the recommended fuel to use is Ultra-low Sulfur Diesel 1–D or 2–D only. At temperatures below -7°C (20°F), it is recommended to use a diesel fuel, which has been seasonally adjusted for the ambient conditions.
Third generation (2011-2019) and fourth-generation (2020-Present)
The third and fourth generations have had three gas engines, 6.2L / 6.8L (both gens) with 6.8L replaced by 7.3L in 2020. Ford recommends Top Tier gasoline to help minimize engine deposits and maintain the optimal vehicle and engine performance. If the engine is so designed, Flex Fuel can also be used.
Where TopTier gasoline is not available, Ford recommends regular unleaded gas with a minimum octane rating of 87. Also recommended is the use of reformulated gasoline with oxygenating content up to 10% ethanol or 15% MTBE (methyl tertiary-butyl ether).
The diesel engine used for these two generations is a 6.7L V8. Ford recommends TopTier diesel fuel where available. TopTier fuels are designed to minimize engine deposits and maintain the optimal vehicle and engine performance.
The following is from F250/350’s owner manual.
You should use Ultra-Low Sulfur Diesel fuel (also known as ULSD) designated as number 1-D or 2-D with a maximum of 15-ppm sulfur in your diesel vehicle. You may operate your vehicle on diesel fuels containing up to 20% biodiesel, also known as B20. These fuels should meet the ASTM D975 diesel or the ASTM D7467 B6-B20 biodiesel industry specifications. Outside of North America, use fuels meeting EN590 or equivalent local market standards.
What Types Of Gasoline Can And Can’t Be Used?
Starting in 1970, EPA required car and petroleum manufacturers to meet the strict requirements on emission regulations for cleaner air. In this regard, car manufacturers invested in producing efficient engines and emission control systems while petroleum producers came up with cleaner and efficient fuels.
The emphasis is to use clean-burning fuels, and that is why car owner manuals now include comprehensive information regarding recommended and non-recommended fuel types. In the next couple of sections, we will briefly discuss fuels that Ford does not recommend for use in its vehicles.
The RFG program has been mandated by congress since 1995, and its second phase started in the year 2000. Reformulated Gasoline (RFG) burns more cleanly compared to conventional gasoline. Therefore, it produces fewer toxins, limiting the smog formation and polluting agents that contaminate the air we breathe.
RFG contains lower amounts of those chemical compounds, which contributes to ozone and air toxins specifically. Ozone is a poisonous gas that is beneficial only if it is up there but harmful when present down here.
Another benefit of reformulated gasoline is less evaporation in hot weather, making it more favorable than conventional gas. RFG is further oxygenated to increase combustion efficiency and reduce carbon monoxide emissions.
The toxins are significantly reduced by using the reformulated blends. Thus, all manufacturers recommend using reformulated gasoline. Ford recommends not to use reformulated gasoline that contains MTBE greater than 15% or ethanol more significant than 10%.
Gasoline/Oxygenated Blends Or E-85
Oxygenates are chemical compounds that have oxygen as part of their molecular structure. Ethanol is one of the most popular oxygenate that is used in gas. To meet the federal mandate, most of the finished gasoline sold in the USA contains 10% ethanol.
For Flex Fuel vehicles, Ford does not recommend the use of ethanol-blended fuel in which the percentage of ethanol is more than 85%. For non-Flex Fuel vehicles, the ethanol percentage should not exceed 10 percent which is the case of regular unleaded fuel.
If your car’s fuel cap is yellow-colored, then it is safe to use Flex-Fuel.
Gasoline With Added Materials
Certain materials are added to gasoline to increase octane rating, reduce engine corrosion, or act as lubricants. Adding materials in gasoline allows for higher compression ratios which means that the engine can extract more energy from combustion.
There are a large number of materials that can be potentially added to gasoline. However, not all are useful and hence not recommended to be used in gasoline. Ford only recommends the use of TopTier gasoline in its vehicles. Ford prohibits the use of the following additives in gasoline.
- Fuels containing kerosene or paraffin.
- Fuels containing methanol.
- Fuels containing metallic-based additives, including manganese-based compounds
- Leaded fuel.
Repair of damage caused by the use of prohibited fuels for which the vehicle was not designed may not be covered by the warranty.
Gasoline With MMT
Methylcyclopentadienyl manganese tricarbonyl (MMT) is a popular gasoline enhancer which is produced by Afon Chemicals. MMT is allowed in U.S. gasoline at a level equivalent to 1/32 grams per gallon manganese.
MMT is an octane-boosting additive that has been used for many years. These days, MMT is only used in race gas. In modern-day vehicles, MMT damages the emissions control system thus adversely affection the emissions. Long-term use of MMT will lead to Manganese deposits in the engine, thus causing engine damage. The race engines are only meant for a handful of races while a normal car is meant to be durable.
The following is from the F250/350 user manual.
The use of fuels with metallic compounds such as methylcyclopentadienyl manganese tricarbonyl (commonly known as MMT), which is a manganese-based fuel additive, will impair engine performance and affect the emission control system
Ford recommends the use of diesel that is blended with 20% biodiesel. However certain precautions need to be taken. The following is from the F250/350 user manual.
Diesel fuel is adjusted seasonally for cold temperatures. Diesel fuel, which has not been properly formulated for the ambient conditions may gel which can clog the fuel filters. One indication that the fuel filter(s) may be clogged is if the engine starts, stalls after a short time, and then do not restart. If you have been using biodiesel, you may need to use a fuel with lower biodiesel content, try another brand, or discontinue using biodiesel. Do not use alcohol-based additives to correct fuel gelling. This may result in damage to the fuel injectors and system. Use the proper anti-gel and performance improvement product.
If properly formulated diesel is used, then Ford recommends not to add any aftermarket additives to the fuel tank because these can damage the injector system or engine.
Among prohibited fuels is diesel for agricultural use, home heating, or any diesel not intended for highway use because such fuel may damage the fuel injection system or engine. Additionally mixing gasoline, gasohol, or alcohol with diesel fuel creates a serious fire hazard and engine performance problems and should never be done.
Ford prohibits blending of used engine oil with diesel fuel under any circumstances because this significantly increases the vehicle’s exhaust emissions and reduces engine life due to increased internal wear.
What If I Hear A Knocking Noise From The Engine After Refilling?
A slight knocking is common and can be heard even from a brand new car, but if the sound is a little too obvious then it is advised to use high-quality gasoline, 93 octane preferably, or 91 octane if 93 is not available. It is advised not to use gasoline with less than 87% of octane. If the sound persists even after using premium gas, then your engine might need service.
Knocking occurs when the ignition timing is out of sync or it happens when the fuel is burnt prematurely, not at the optimum temperature range. When the air-fuel mixture burns in the cylinder in several small pockets without the spark, the precise piston stroke is no longer there and the shockwaves produced from the abrupt small blasts, the characteristic metallic pinging sound is heard.
The whole process pressurized the cylinder a lot. The result could either be inconsequential or completely devastating. If a loud knocking sound is heard then it’s best to have it diagnosed at an authorized dealership or a trust auto shop where you can get a proper verdict on the underlying cause.
The F250/350 owner manual states the following:
“Do not be concerned if your engine sometimes knocks lightly. However, if it knocks heavily under most driving conditions while you are using fuel with the recommended octane rating, see your authorized dealer to prevent any engine damage.”
Also read: 8 Common Problems Of A Ford F-250
Does the Ford F250/350 Have Good Gas Mileage?
The U.S. Department of Energy tabulates vehicle fuel economy data which can be found at https://www.fueleconomy.gov. This data is very reliable and includes city, highway, and combined miles per gallon figures. However, it does not gather data for any Heavy Duty trucks irrespective of the manufacturer.
This then makes the gathering of reliable fuel economy data quite tricky. The data shared in the following tables are for combined averages and are only intended to give an idea of the fuel economy of F250/350. We’ll first discuss all the gasoline engine and then continue with the diesel engines.
5.4 L Engines With Regular Gasoline
5.4 L Engines With Flex Fuel
6.8 L Engines With Regular Gasoline
7.3 L Engines With Regular Gasoline
6.0 L Diesel Engines
6.4 L Diesel Engines
6.7 L Diesel Engines
7.3 L Diesel Engines
What’s The Gas Tank Size Of The Ford F250/350?
Presented below is tank size data available in all four generations of F250/350. Different tank sizes are available based on cabin size, and below, we present comprehensive data in tabular form.
1994 – 2004
2005 – 2007
2008 – 2010
2011 – 2016
2017 – 2019
2020 – 2021
How Much Does It Cost To Fill Up Ford F250/350?
As of November 1, 2021, the average cost of Ultra Low Sulfur Diesel in the U.S. is $2.45. Based on this value, the cost of filling a Ford F250/350 could range from $ 46.55 to $162.93, depending on the size of the tank as given in the section on gas tank sizes.
Similarly, the current average price of regular unleaded gas in the U.S. is $3.42. The gas tank size over the four generations could cost anything from $64.98 to $164.16 to fill the F250/350. In California, a single gallon costs $4.706, and if you happen to have the biggest fuel tank, you will spend about $225.
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