What’s Better For Your Car: Synthetic Or Conventional Oil?

What’s In The Oil?

The basic kind of oil is a by-product of refined crude oil that comes out of the ground (often referred to as ‘base’ oil). Refining helps reduce the impurities in the oil, but the end product has molecules that vary in size. This inconsistency in size can result in restricted flow when working its way through the engine. Synthetic oil, on the other hand, contains molecules that are manufactured and are all the same size and shape. This uniformity creates less friction in the engine and allows the oil to move throughout the engine smoothly thereby providing better performance.

Additives added to the base oil are what give the oil the characteristics it needs to do its job. Although additives are typically only 15 to 25 percent of the make-up of motor oil, they can impact a lubricant's performance much more than the base oil. For example, mineral-based motor oil with a very good additive package can easily outperform synthetic motor oil with a mediocre additive package. There is no easy way for a consumer to determine the quality of motor oil’s additive package. While, price is one way to judge the quality, since the more advanced additive technologies cost more to produce, performance is the ultimate measure of additive package quality.

The ongoing development of these additives are a major part of the reason that cars can now be driven 5,000 or more miles between oil changes that used to have to be made every 3,000 miles. And some newer blends are now touting that they can give your car 10,000-12,000 between oil changes. This not only saves time and money but it is also good for the environment since less oil will need to be disposed of. By the way, if you get your oil change and a quick service type of facility or from a mechanic that insists on changing the oil every 3,000 miles even though you have a late model car quickly find another service center – someone is trying to pull a fast one on you. If, however, you drive a 10-year-old car or older, stick to that 3,000 mile oil change schedule.

Which Oil To Buy

So, how do you know which oil is best for your car? There are a number of factors to consider. First, check to see what your car’s manufacturer recommends. In some newer vehicles there are even issues governing the use of certain oils and gasoline blends to be used in order to maintain the car’s warranty. The type of car you drive is also a factor. Sports and high performance cars, as well as large cars that may haul heavy loads have particular needs including the oil. Older cars may need special consideration as well.

But, there is a price to pay when using synthetics. They almost always cost more than conventional oil. But, you’ll have to do some calculating to determine if the less frequent oil changes with synthetic balance its higher cost.

Do Brands Matter?

The prices of motor oils – whichever kind you buy – vary greatly. You can pay a high price for one brand and then see the exact same brand sold for less at another store. Oil manufacturers know that drivers get in the habit of sticking with a product they know and/or have used in the car since they bought it. Mechanics tend to stick with one brand for the cars they service.

From my research, however, all brands are pretty much alike. The well-respected Consumer Reports said while brands of motor oil don’t matter all that much, what is important is its viscosity grade (that’s the 10W-30, or similar number/letter combination you’ll find on the product - the two numbers refer to the oil’s viscosity properties during a cold start; the W stands for “winter”). It’s hard for a layman to know what that means for your particular car, so I’ve found the best advice is to rely on your mechanic, or even better, follow what it says in the car’s manual. The manual may also suggest whether you should use synthetic or conventional oil.