Despite all the 3.5 EcoBoost problems that we've mentioned thus far, as a whole, they're quite robust. Ford engines are typically durable and long-lasting, and the EcoBoost is no different. Most estimates for a 3.5 EcoBoost V6's life expectancy should be around 250,000 miles (or around 402,000 kilometers). Once that threshold is passed, you'll need some serious engine work and rebuilding. Although, owners are more than able to extend this lifespan by being diligent about maintenance and servicing.