Here's why:
* Ford's Recommendation: The Ford owner's manual for your Ranger likely recommends a different viscosity, like 5W-30 or 10W-30.
* Climate: 10W-40 is thicker than 5W-30 or 10W-30. This can cause increased wear on engine parts in cold weather, as the thicker oil takes longer to reach all parts of the engine. If you live in a cold climate, it's best to stick with a thinner oil.
* Engine Performance: Thicker oil can lead to slightly reduced engine performance, especially during cold starts.
* Fuel Economy: While the difference is small, 10W-40 can slightly decrease your fuel economy compared to a thinner oil.
However, 10W-40 can be beneficial in certain situations:
* High Temperatures: If you live in a hot climate and experience high engine temperatures, 10W-40 provides better protection against oil breakdown at higher temperatures.
* High Mileage Engines: In engines with high mileage, 10W-40 can offer slightly better protection against wear.
* Engine Modifications: Some modifications, like high-performance cams or turbochargers, may require a thicker oil like 10W-40.
Before you make a decision:
* Check your owner's manual: It will provide the specific viscosity recommendations for your engine.
* Consult a mechanic: They can advise you based on your driving conditions and any specific engine needs.
Ultimately, it's best to follow the manufacturer's recommendations for your vehicle, unless you have specific reasons to deviate.
