Produced at the Cleveland Engine plant in Brook Park, Ohio from 1964 through 1996, the 240 and 300 Sixes are well known for their durability. Simple design and rugged construction continue to endear these engines to a number of Ford enthusiasts to this day. Many have run 300,000 to 600,000 miles (480,000 to 970,000 km) without any more service than standard oil changes.[citation needed] The engine has earned the monikers "bulletproof" and "indestructible" by many. There are numerous claims of those who have purposely sought out to destroy one through abusive use, and were unsuccessful in doing so.
One example of the engine's sturdy design is the fact that no timing chain or timing belt (both of which can break, causing unwanted downtime or even engine damage) is used. This generation of Ford Six was designed with long-wearing gears for that purpose instead. Very few modern engines use timing gears; belts and chains are by far more common.
Both the 240 and the 300, no matter the application, used a single barrel Carter YF carburetor until the introduction of Electronic Fuel Injection. With proper gearing, many F-trucks and Broncos are able to achieve over 30 mpg with these carburetors, when properly tuned. This was heavily used by Ford's advertising campaign (some television advertisements and written literature even claimed 30 mpg), since the V8 engines in these trucks rarely achieved over 14 mpg. Modern rebuilds are possible to reach 40 mpg in some cases.
The fuel economy of the 300 makes the engine a popular choice amongst truck enthusiasts that want both power and economy. The addition of performance parts (such as intake and exhaust manifolds with a four-barrel carburetor) place the engine power output near the same levels as the stock HO (high output) version of the optional 351 V8, with little or no change in economy. There are claims of 300s that have had the power output doubled, or even tripled, with less than a single mpg drop in fuel economy.
