Is a Ford F-150 with 250,000 km worth buying, or is that too many kilometers for a truck?

At 250,000 km, engine choice on the F-150 determines everything. There are two very different answers depending on what you find.

The 5.0L V8 (Coyote): this engine is proven and owners report it running well beyond 300,000 km with proper oil changes. At 250,000 km, a well-maintained 5.0L is a realistic work truck. Check for oil leaks around the valve cover gaskets, which are common at this mileage, and listen for any ticking at startup. Otherwise the drivetrain holds up.

The 3.5L EcoBoost: significantly more risk at 250,000 km. The turbochargers, intercooler, and direct injection system are expensive to repair and common failure points after 200,000 km. The timing chains and chain guides on the early EcoBoost (2011 to 2016) are a known issue. Budget for a potential $2,000 to $4,000 repair if you buy this version.

The 2.7L EcoBoost: has had port injection added in newer years which reduces carbon buildup, but the same general caution applies at high mileage.

For occasional towing at 250,000 km: be conservative. Have the transmission fluid and differential fluid checked. The 6-speed automatic on these trucks handles towing well when serviced, but at this mileage with unknown fluid history, expect fluid changes as an immediate cost.

At $18,000 CAD, a 5.0L F-150 with records is a defensible buy. The same price for an EcoBoost is not. If you cannot find a 5.0L in budget, look at the Nissan Frontier with the older 4.0L V6, which is consistently praised for proven reliability at high mileage and sells below Tacoma prices.