How often should I change the oil?

We’ve researched this and find that many “experts” disagree on exact numbers. First, check your vehicle owner’s manual. If you don’t have that or need a second opinion, here are some recommendations we’ve come across:

Many new vehicles have computers in them that keep watch on various engine conditions, and these computers do a good job of letting you know when it's a good time to get the oil changed. The actual mileage can vary depending on a number of factors, including the ambient temperature and how hard you've been working the engine. If your car or truck doesn't have this type of system, here are some guidelines:

With a new engine with little or no wear, you may be able to get away with 7,500 mile oil changes (or even longer, as some manufacturers say). But as an engine gets older, "blow-by" increases. This is because the rings and valves are not as tight as when new. More unburned fuel gets by into the crankcase, and this dilutes the oil, causing the oil to break down sooner. So if the oil isn't changed often enough, you can end up with accelerated wear in your engine.

 SO... we recommend changing the oil every 5,000 miles if you're using conventional oil, and every 7,500 miles* with full synthetic oil. For older engines, 5,000 mile intervals are still OK, but if you want the engine to last a long time, you can change to "High Mileage" oil, which includes additives that help prevent and rid the engine of small leaks, deposits and sludge. High Mileage oil also usually includes special anti-friction additives which newer engines do not need as much.

*Audi, Jaguar, Mercedes and others have started to use only synthetic oils in their new cars, and they recommend changing the oil every 10,000 to 12,000 miles, depending on the car manufacturer. BMW recommends 15,000 miles, but we have photos of BMW engines that had their oil changed at 15,000 mile intervals, and there is too much sludge build-up. Toyota is now using and recommending synthetic oil in many of their new vehicles, and they recommend changing the oil every 10,000 miles.

There are still guys out there who change their oil every 3,000 miles "because that's what my dad did, and his cars ran forever". Actually, modern oils are far superior to what Dad used, as are modern oil filters. Also, today's engines are a result of much better engineering, with tighter clearances between parts, and are made from improved materials (metals and alloys). So they do not need the oil changed at 3,000 miles anymore.

In summary, for most vehicles we recommend changing conventional oil every 5,000 miles and synthetic oil every 7,500 miles. The oil filter should be changed at the same time the oil is changed.