If there’s one thing F-150 owners agree on, it’s that the optional larger fuel tank changes everything.

On the r/f150 subreddit this week, dozens of owners recently compared notes on the truck’s smaller standard tanks and the optional 36-gallon upgrade. If a new buyer says nothing when building one out, the F-150 comes with a 23 or 26 gallon capacity, depending on year.

But most said the upgrade is worth every extra penny

One user in Illinois mentioned being able to make a full round trip to Michigan’s Upper Peninsula and back on a single tank.

Another driver from Indiana said the 36-gallon setup lets them cruise from Fort Wayne to Panama City Beach with just one fuel stop.

In short, the F-150 36-gallon “extended range” tank isn’t about bragging rights.

It’s about fewer gas stops, especially for long hauls, towing, or hunting trips in remote country.

But it’s also a love-hate relationship

Several owners joked about the sting of triple-digit fill-ups, with one saying they fill up at half a tank just to “spread out the pain.”

The smaller tank owners mostly complained about visiting the pump too often or being “shaky on E,” as one put it.

So if you’re shopping for a used F-150, it’s worth knowing how to tell which tank your potential truck has.

Here’s how to find out an F-150’s fuel tank capacity before you buy

1. Know which trims usually have it

The 36-gallon option shows up most often on SuperCrew and SuperCab trucks with the 2.7L or 3.5L EcoBoost or 5.0L V8 engines.

It’s available on trims like the Lariat, Tremor, King Ranch, and Platinum, though even base XL models could be ordered with it.

If you’re looking at a regular cab or a short-wheelbase truck, odds are it’s the smaller tank.

2. Look for the “Extended Range” description

Ford doesn’t really advertise the 36-gallon setup as a separate trim, but most listings (especially from dealerships) note it in the description.

Keep an eye out for “extended range” or “36-gallon fuel tank” in the features list when browsing used trucks.

3. Check the Window Sticker

If you’re hunting on a Ford dealer’s lot, the most reliable method is the original Monroney sticker.

It lists the exact factory-installed equipment, including the tank size. If you see “36-gallon extended range fuel tank,” that’s your confirmation.

Dealers often keep digital copies, and many can still be pulled online using the truck’s VIN.

4. Check the Owner’s Manual

The owner’s manual has a section titled “Capacities and Specifications.” Flip to that page and match the number listed under “Fuel Tank Capacity.”

Manuals can differ slightly by year and drivetrain, so double-check that it matches your specific configuration.

5. Run the VIN through a vehicle spec tool

Sites like Carfax or Ford’s official VIN lookup can tell you exactly what was factory-installed on the truck, down to the tank size. It’s especially useful if the window sticker is missing or you’re buying from a private seller.

6. Call any certified dealership’s parts department with the VIN

I learned this one from my service writing days. While any of the above might reveal the true specs just fine, there’s nothing like calling a parts department and having them confirm a replacement tank’s part number.

According to Ford OEM Parts Online, 2015 to 2025 F-150 models all use the same 36-gallon tank. Its part number as of this writing is KL3Z-9002-E. Keep in mind Ford updates part numbers over time, so older models have a different number, but the one listed here is likely the most current replacement.

Ford doesn’t always spell it out clearly, but with a bit of digging, you can avoid owning a truck that stops for gas twice as much

The standard 23- or 26-gallon tank might work fine for commuters, but for drivers who’d rather skip a few gas stations (and can stomach the triple-digit fill-ups) the 36-gallon tank is the one to hunt for.