Synthetic Vs. Conventional Oil: What’s the Difference?

Did you know that synthetic oil wasn’t widely used until 80 years after Karl Benz created the first real automobile in 1886? Until synthetic oil hit the mainstream market in 1966, cars ran on conventional oil that was often crude.

Both conventional motor oil and synthetic motor oil have become refined over the years. In this article, we’ll explore the main differences between both types of motor oil.

Conventional Oil and Synthetic Oil Defined

Pour oil

Conventional oil is fossil oil (or dinosaur juice). In order for conventional oil to work optimally in engines, it must be as clean as possible. So modern conventional motor oil is heavily filtered before hitting the shelves.

Synthetic oil is a lubricant that’s made by chemical compounds. Sometimes synthetic oil will contain chemically altered petroleum components. It was invented to solve some of the problems surrounding conventional oil.

Why You Should Avoid Synthetic Blends

Synthetic blends are a mixture of synthetic oil and conventional oil.

You may be tempted to save a few bucks on a synthetic blend. We’re telling you that it’s a bad idea. First of all, synthetic blends aren’t regulated and you’d be taking a gamble on the quality of the oil. Second, you might be overpaying for the blend because it may contain 99% conventional oil and only 1% synthetic oil. Blends don’t offer the same kind of protection as pure synthetic oil does.

To compare both types of motor oil, let’s go over the three most important factors to consider:

1. Oil Change Intervals

Synthetic oil is cleaner than conventional oil, which means it doesn’t need to be changed as often. Typically, conventional oil starts to go bad after running through the engine for 3,000 to 5,000 miles. Synthetic oil usually lasts 3-5 times as long, between 10,000 and 15,000 miles.

2. Engine Wear Protection

The whole point of having oil in your motor is to keep the engine parts lubricated at all times. Many engine parts are always rubbing against each other while moving at high speeds. Without oil serving as a slippery barrier between the parts, they will grind together and wear down quickly.

Which type of oil provides better, more consistent lubrication?

Synthetic oil. It’s because conventional oil breaks down much faster than synthetic oil. When oil degrades, it doesn’t provide as much lubrication.

3. Ability to Flow in Cold Temperatures

When the engine is off, the motor oil sits in the oil pan. Conventional oil gets a little thicker in cold temperatures when it sits for a while. When you fire up the engine, it takes a while for conventional oil to warm up and achieve the right thin, runny consistency to flow through the engine.

Synthetic oil doesn’t have that problem. It doesn’t contain hydrocarbons that thicken up in cold temperatures. Synthetic oil is engineered to flow right through the engine as soon as you start it up.

If you ask for our opinion, we’d recommend synthetic oil over conventional oil every time. The only saving grace of conventional oil is the fact that it’s cheaper than synthetic oil.

Which Type of Oil is Better For My Car?


Synthetic oil is superior to conventional oil in so many ways. So many manufacturers design modern cars to accept only synthetic oil. In modern cars, you’ll find seals and other components that are designed to work well with the chemicals found in synthetic oil. In older cars? Perhaps not.

Many older cars have seals and other components that are worn. Synthetic oil has detergents that could push out deposits that have been acting as seals. This could encourage leaking. Don’t let the old engine design in your car keep you from considering synthetic oil, though! Switching to synthetic oil could prolong your car’s life.

We suggest bringing the car to an experienced technician and have him/her make the necessary seal replacements first. Once your technician gives your car the green light to run on synthetic oil, you should be good to go.

However, before you go through all that trouble, take the time to decide whether switching to synthetic oil is even worth it. Even though synthetic oil generally works better than conventional oil, it may not be the best option for your car.

Sometimes it’s just easier to stick to conventional oil if:

  1. Your commute is long enough for the engine to fully heat up. It takes a while for conventional oil to heat up and properly lubricate your engine, but when it’s hot, it’s pretty darn effective. That’s why synthetic oil – which is made to perform well when it is still cold – might be overkill if your commute is longer.
  2. Your car consumes at least 1-2 quarts of oil between oil changes. Older cars consume synthetic oil faster than conventional oil because it is always thin. If your car already consumes more conventional oil than usual, then there’s no sense in splurging on synthetic oil if it’s just going to get burned.
  3. Your car has an engine that’s prone to oil leaks. Synthetic oil is more likely to leak through bad seals. If your engine already has a leaky seal or two, synthetic oil is just going to leak out faster. Conventional oil is the safer choice in this situation.


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