This question is always confusing. But we're going to clear it up for you. Ford Motor Company says that 7,500-mile intervals are sufficient for most vehicles operating under normal conditions. They also indicate that under Special Operating Conditions that the oil should be changed at 5,000 miles, which is what we recommend. Special Operating Conditions include stop-and-go driving, trailer towing, extensive idling and/or dusty conditions. Most of us encounter one or more of these conditions.
Unless you encounter all of the conditions 5,000 miles is an adequate maintenance interval. Even if you exceed the recommended mileage slightly, you're still OK. If you encounter all of these conditions you may want to stick closer to a 3,000-mile interval. NEVER, EVER should you exceed the 7,500-mile maximum interval.
If you drive a diesel, you should change your oil at 200 hours or 5,000 miles, whichever occurs first.
Remember, also, that all of the maintenance intervals were developed using Motorcraft Semi-Synthetic oil, the oil designed by the engineers who designed your vehicle. Many lube shops or tire dealers use cheaper organic-blended oils. These oils will breakdown prematurely under the conditions that these engines operate. Treat your investment right; use Motorcraft brand oils and filters.
Ford recommends testing the coolant every 30,000 miles on gasoline engines and 20,000 miles on diesels. We have found that more often than not the coolant fails prior to the life expectancy. This could be contributed to our unique climate and driving conditions. We also find that most coolant related engine failures occur before 100,000 miles.
If these are the only times that you experience this sensation it is a normal condition. It is merely your anti-lock braking system actuating. The wheel sensors indicate lock-up which causes it to pulsate the brakes. This prevents the vehicle from sliding sideways in a poor-traction situation.
Generally, fuel economy is determined by driving habits. Some examples include: