10 Best Motor Oils 2024 in the United States

Since automobiles are such an investment nowadays, people will want to keep using them for a good number of years. It's not uncommon to have a car go over 100,000 miles. But you need a lot of maintenance if you want to keep a car running that long. Motor oil is an important part of keeping your car in good condition. Motor oil is used in lubricating and cooling engines by reducing the friction between the parts. It also prevents rust, by shielding metal parts from oxygen in the air. It also is used to clean the motor. But you have to know what motor oil is best for your car, and at what price. It's also good to know how often to change your oil. You'll have to change after your car goes a few thousand miles. Here is a guide to some of the best motor oils on the market.  

• Conventional Motor Oil—these are petroleum- based oils. They are more sensitive to temperature changes, and can more likely to experience thermal viscosity breakdown—where the oil behaves very differently at high temperatures than what it did at low temperatures. High viscosity means that the oil adheres better to the engine and protects the engine parts better. Petroleum is distilled at an oil refinery to get out impurities in order to make motor oil. There will always remain some impurities, and these impurities will cause breakdown at high temperatures. If you change the oil frequently, it should prevent thermal viscosity breakdown.

• Full Synthetic Motor Oil—Synthetic oil lets the engine operate at higher temperatures. They are more resistant to thermal viscosity breakdown than petroleum-based motor oils. Some people say that it allows for longer intervals without changing oil, as well as less wear on the parts.

• Blended Motor Oil-- This is a mixture of synthetic and conventional motor oils. This will achieve some of the greater temperature range of synthetic oil, but at a lower cost (pure synthetic oil tends to be more expensive).

• Single-viscosity (Single-grade) oil: There are 11 viscosity grades: 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. The 6 that are designated with a W are for Winter, and 5 that are without the W designation are for high temperatures.

• Multi-viscosity (Multi-grade) Oil: Multi-grade oils combine two motor oils together. They have the viscosity of one type of oil when cold, and the viscosity of a second type when hot. This allows you to use the same oil the whole year 'round. 

• When to change oil: Some users recommend changing their oil every 3000 miles. Synthetic oil is supposed to allow you to change the oil after accumulating more miles—up to 10,000 miles, with a high quality, extended-interval oil filter. The OCI (=Oil Change Interval) statistic is what tells you how often to change oil. It is recommended to change oil every 4000 miles, or 4 months of use. Never use the same oil for more than 6 months.

• Torque settings: After draining out the old oil, attach the oil drain bolt at the manufacturer's torque settings, so that it won't leak. And don't twist it on too much, because you may ruin the threads.

• Changing the filter: When you change the filter, apply some motor oil on it, so that when you start the engine, there won't be metal-on-metal friction.

• Know how much oil to put in the engine: Read the oil level with the dipstick only when 1) the car is level, and 2) the engine is cool. Add the amount of oil that the manufacturer recommends. If you didn't put in enough, you can always add more. But if you put in too much, it's a hassle to drain out the excess. The car will not run efficiently with too much oil, because the crankshaft will be running in the oil. This will cause the oil to foam up, and not efficiently lubricate the engine. Running an engine in this state could actually damage it.

• Viscosity: The viscosity is the ability of the oil to flow. The lower the viscosity, the thinner the oil and the more easily it flows. The viscosity is listed as a pair of numbers, such as 10W-40: 10W indicates how the oil flows in Winter; 40 indicates how it flows at high temperatures. The lower the first number is, the more effective the oil works in cold weather. If you live in an area where the winters are mild, you can settle for a higher first number. But the best thing is to match the oil to your vehicle's model.

• Thermal Breakdown: A motor oil's performance is measured by its viscosity. Motor oil has what is called thermal viscosity breakdown: the hotter it gets, the viscosity goes down a lot, and the worse it is in trying to reduce heat and friction.

• Detergency: Motor oils also have additives, like detergents and dispersants, that help keep the engine clean. Detergents remove solid deposits on the engine parts, and dispersants keep these deposits from compacting back together again. The oil picks up the soot from the burning of the fuel—that's what makes the oil come out black when you change it, instead of the amber color that it had originally. Certain motor oils' detergents are so good at cleaning the engine, they may clog up the oil filter.  

Royal Purple—is a lubricant manufacturer that was founded in 1986 by John Williams. Their headquarters is located in Porter, Texas. They make lubricants for automobiles, industry, motorcycles, and marine use.

Shell—was founded by Marcus Samuel in 1833. He was selling antiques and oriental shells, and wanted to expand his business by importing shells from the Far East. His sons started bulk transport of oil, and in 1897 renamed their company the Shell Transport and Trading Company. Their products include oil and fuel, and they are involved in exploration, production, and refining of petroleum products.

Pennzoil—was founded in Los Angeles, California in 1913, but they presently have their headquarters in Houston, Texas. They are manufacturers of full synthetic motor oils, conventional motor oils, automobile filters for oil and air, as well as gasoline. They were acquired by the Shell group in 1999.

Castrol--is a manufacturer, distributor and marketer of premium lubricating oils and greases for automobiles, marine craft, and industry. They were founded as the Wakefield Oil Company by Charles Wakefield in 1899. Their headquarters is in Pangbourne, Berkshire, United Kingdom.