How to Purchase the Best Motor Oil for Your Car

Whether it's to take care of a brand new Lexus or to extend the life of your 1998 Toyota, good car maintenance is simply a fact of life. It's important not to overlook any aspect of car care, and that begins with changing the oil. Motor oil is perhaps the most important component in your vehicle's internal combustion engine, as it lubricates and cools the thousands of moving parts that work together to power your vehicle; though not an unusual way to make your car last longer, it's still important. It's not enough to simply pick up the first oil you see on the shelf and then forget about it: you must regularly check your oil levels, adding or replacing oil as needed, and you must use a good quality oil that meets the requirements of your vehicle.

The first step in taking care of your engine is to purchase the best motor oil for your needs. If you don't know much about cars or this is your first time buying your own engine oil, it can seem like a daunting task. There are a plethora of brands advertising motor oil with unfamiliar terminology, confusing numbers, and at drastically different prices. Half the battle is simply knowing the standard accepted variety of motor oil for your vehicle, however there are still a few decisions you have to make. This guide will provide the knowledge you need to make those decisions and purchase the best motor oil for your vehicle, even if you aren't really a car person.

Not all oils are created equal. There are conventional and synthetic varieties as well as blends of the two. While conventional oils are cheaper, full synthetic varieties hold up better under extreme temperatures (particularly extreme cold weather). Synthetic oil is also more reliable if you put your vehicle through strenuous conditions, such as pulling a trailer or carrying other types of heavy loads. Finally, synthetic oil contains fewer imperfections than its conventional counterpart, leading to longer life, less sludge buildup, and all-around better performance. If you want to purchase the best motor oil at any price, a full synthetic oil will be your best bet.

Conventional oil's biggest advantage is its affordability compared to synthetic engine oil. Generally speaking, it performs slightly worse than synthetic in just about every category, but it's important to note that conventional and synthetic oils contain the same additives. All motor oil contains antirust, anti-wear, detergent, dispersant, and other additives, so you'll receive all those benefits even if you purchase the cheaper conventional varieties of oil. So while synthetic oil is an step up from conventional oil, you may decide it isn't worth the extra expense if you don't put your vehicle through extreme temperatures or strenuous loads. You will, however, need to change your oil more often compared to synthetic oils.

The synthetic blend variety of motor oils came about as an attempt to capture the best of both worlds: a midway point between the affordability of conventional engine oil and the enhanced performance of full synthetic oils. The results are generally mixed (no pun intended), as even the best synthetic blend can't come close to matching the performance of a full synthetic oil. However, synthetic blends do provide a decent change interval. Roughly speaking, the average synthetic blend can go about 7500 miles without needing a change, compared to 5000 for conventional oils and 10,000 for full synthetic oils.

When it comes to cost, synthetic blends are significantly cheaper than full synthetic offerings from the same brand, and are often almost as cheap as conventional oils. If you're looking to purchase the best motor oil without springing for the more expensive synthetic varieties, a blended option may be right for you. You should understand the caveat that most of the benefits of a full synthetic oil are drastically muted in a blend, but the improved change interval alone may be reason enough to go this route with. If you don't rack up that many miles on your vehicle and regularly change your oil anyway, then you might as well save your money and stick with conventional.

Most engine oil manufacturers now offer oil specifically marketed toward vehicles with 75,000 or more miles of use. The jury is still out as far as whether high mileage oils really make much of a difference. The way this breed of motor oil is supposed to work is by conditioning the valves and seals of older engines with special additives. High mileage oils also tend to be on the higher end of the viscosity range, leading to lower efficiency but generally better seals on your piston rings. If you're looking to purchase the best motor oil for a vehicle with 75,000–100,000 miles on it, then you might consider looking into high mileage oils (which, by the way, also come in conventional, synthetic, or blended varieties). Be aware, however, that you might not notice that much of a difference in performance, especially if you change your oil regularly.

Picking the Right Viscosity

The viscosity rating on your motor oil, such as 5W-30 or 10W-40, refers—obviously enough—to the actual viscosity of said oil. SAE International provides viscosity grades from 0-60, and the motor oil rating is actually a range of the oil's viscosity in low and high temperatures. So for example, 5W-30 refers to an oil with a viscosity of 5 during a cold start (the "W" stands for "Winter") and 30 when the engine has heated up after running for a while.

The good news is that you don't need to understand any of that. Simply put, different viscosity oils are optimized for different engines, so there's not really a "trick" to using a certain viscosity oil at different times of the year or anything. When you're looking to purchase the best motor oil for your vehicle, simply buy the viscosity recommended by your vehicle's manufacturer. You can find that information in your owner's manual, online, or by reaching out to a mechanic or the manufacturer itself.

Finding the Best Brand

If you're on a mission to purchase the best motor oil for your vehicle, you may find yourself scouring the internet for reviews to try and figure out which brand's oil is the best fit for your needs. However, the American Petroleum Institute (API) tests every brand of motor oil sold in the United States. Every oil found to meet the API's minimum requirements will feature the API's star logo on its packaging. As long as you see this logo, you can be assured that the oil performs up to its specifications. All major engine oil producers—Mobil 1, Royal Purple, Valvoline, etc.—have API approval, so there is actually little to no functional difference between the major brands, as is the case with car detailing products that make your car look brand new.

As long as you purchase the right viscosity level (eg, 5W-30) for your vehicle, it doesn't matter whether you use Pennzoil or Castrol or any other brand. However, most mechanics don't recommend generic brand motor oils: they don't go through as much testing, and usually the price difference is only a matter of cents anyway. The smart move would be to buy whatever name brand happens to be on sale when you're out buying motor oil.