Home Car Tips Comparison of Conventional Motor Oil and Synthetic Motor Oil

Comparison of Conventional Motor Oil and Synthetic Motor Oil

by Frank
difference between traditional and synthetic oil

All vehicles consume oil, but how often one needs to change their car’s oil depends on two factors: the car’s engine design and the operator’s driving style. When the time comes to take a car to the auto shop for an oil change, the mechanic may ask the car owner whether the oil should be replaced with conventional, traditional motor oil, or synthetic oil.

Once only common among high-performance cars, synthetic oil has quickly taken hold of the majority of new and old vehicles. According to the 2018 National Oil and Lube News annual survey, more than half of car owners have now chosen synthetic or synthetic blends when changing their oil. Nonprofit consumer organization Consumer Reports also found that around 70% of new cars in the 2019 model year were filled with either fully synthetic or blended oil. Automakers such as Honda are not making synthetic oil a requirement for their engines, but they do use synthetic oil to improve engine efficiency.

The question is, does switching to synthetic motor oil positively impact all cars?

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How motor oil works

Often referred to as the lifeblood of vehicles, motor oil lubricates the engine’s key components, protecting them from corrosion and keeping them cool. Most of the oil is normally composed of a base oil made of petroleum, synthetic chemicals, or a blend of both that acts as the main lubricant. The rest of the oil is composed of additives that dictate the oil’s viscosity.

As the engine oil enters the car’s engine, it circulates around the car’s engine oil pump, pickup tube, oil filter, and pressure relief valve, among others. By doing this, it coats the components to prevent excessive friction between them. At the same time, the oil can clear the engine of dust and dirt.

Eventually, the oil can break down and clog the oil filter with contaminants. Oil can also get stuck in the combustion chamber, or evaporate in the exhaust valve due to high temperatures. While oil consumption largely depends on the make of each vehicle, drivers also play a part in how often their car oil needs to be changed because more oil is consumed when the speed of the engine increases. There is no denying that every vehicle’s oil needs regular changing, but things can get a bit confusing when deciding between traditional and synthetic oil.

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The difference between traditional and synthetic oil

Traditional oil is refined from the naturally-occurring, unrefined petroleum product of crude oil, while synthetic oil is artificially created from chemical compounds meant to mimic the best aspects of crude oil. Synthetic oil can be sold as either fully synthetic or as a blend made of multiple base oils. Full synthetic oils are made without petroleum and have additives to aid in the oil’s degradation, while synthetic blends add a bit of the protection of full synthetic oils while still using conventional oil. The American Petroleum Institute classifies base oils into five categories, with the first three of those refined from petroleum crude oil, the fourth category covering full synthetic oils, and the fifth category for every other base oil.

Which is better?

For individuals who may have trouble choosing between traditional and synthetic oils, here’s a quick comparison between the two. It is important to note that additives may have a significant effect on an oil’s performance, so do not forget to look past the base oil and look into which additives each oil offers and how they can benefit the vehicle.

Synthetic oils are less prone to chemical degradation than traditional oils. When exposed to water contamination, extreme heat, fuel contamination, and other dangerous conditions, traditional oil may degrade and cause corrosion. It can turn into sludge and deposits, reducing the engine’s efficiency. It can also evaporate in the engine’s exhaust stream due to heat. Synthetic oil can withstand many of these conditions because it has better oxidation and high-temperature stability, protecting against breakdown.

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Synthetic oils have a higher viscosity index than traditional oils. Traditional oils can become thick when extremely cold, causing the oil to become stuck and preventing it from circulating in the engine, adding to the possibility of engine failure. Synthetics, on the other hand, can handle temperature changes better, allowing the oil to remain thin and continue coating the components to prevent excessive friction.


Synthetic oil is generally viewed as more expensive than traditional oil. However, prices vary based on a specific oil’s brand and formulation. In 2019, the American Automobile Association (AAA) reported that five quarts of traditional oil cost around $28, while five quarts of full synthetic oil cost around $45. When including the cost of labor, an oil change with the former will cost approximately $38, rising to $70 with the latter. However, in the long term, the performance of synthetic oil can make up for the difference in price, considering synthetic oils can last up to 25,000 miles.

On the other hand, traditional motor oil must be changed every 3,000 to 5,000 miles. For a person who may be worried about the cost but wants the benefits offered by synthetic oils, synthetic blends can perform better than traditional oil at a lower price point than full synthetics, but the change isn’t too significant. Experts recommend going fully synthetic instead of resorting to blends.

When to use a synthetic oil

Because synthetic oil can withstand extreme conditions, it is generally recommended for high-performance engines like those used in motorsports and those in luxury cars. Engines in extreme conditions like brutal cold and environments with hilly or mountainous terrain may benefit from certain synthetic oils. Synthetic can protect against damage from high ambient temperatures and long but slow trips carrying a heavy load, like that experienced by towing. Auto enthusiasts hoping for long engine life for their vehicle may also want to switch to synthetic.

Check the manual

Most vehicles today can run on either traditional or synthetic oil, but the best step to take is to consult the owner’s manual for the car before making the switch. If a vehicle owner fails to follow the auto manufacturer’s recommendations, the vehicle’s warranty may become void. This means the vehicle may not be covered by the automaker in case of engine failure, even if the change in oil isn’t part of the problem.

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