Synthetic or Conventional Oil: Which is Best for Your Car?

Oil Change

Which do you need for your next oil change?

Wait. What?

That question is enough to send panic shooting through your veins and make your palms sweat. How do I know? Is it a choice? Which is better? Which do I need? Synthetic is SO expensive.

Relax and read on. First, you know need to get an oil change on occasion. Most mechanics recommend doing so every 3,000-5,000 miles, but the frequency depends on the guidelines outlined in your owner’s manual. Mechanics will often ask if you prefer synthetic or conventional oil. Here’s what you need to know to answer that question.

Conventional oil: proof that “natural” does not always = “better”

Oil Change

Getting a regular oil change is important, but do you know which type of oil you need?

Conventional oil comes from beneath the ground. It’s a source of energy that’s provided by the planet. Of course, drilling for oil can be taken too far (we’ll get into how synthetic oil can prevent this later), which is why we should explore alternative energy sources.

Synthetic oil comes from a laboratory. Some brands use conventional oil as a base and change the chemical structure. Others use raw materials to create the product. The specifics aren’t very important. Regardless of how synthetic oil is made, it provides several benefits that conventional oil doesn’t:

1. Temperature control

Extremely hot and cold temperatures place a tremendous amount of stress on your engine. If you live in an area where the summers and/or winters are brutal, you might want to invest in synthetic oil.

2. Fewer oil changes needed

Conventional oil should be changed every 3,000-5,000 miles. Synthetic oil can last 7,000-10,000 miles. Conventional oil changes are cheaper on a “per transaction” basis, but synthetic oil could save money in the long-term. Do the math!

3. Yes, you can switch. 

A lot of people think you can’t switch from conventional to synthetic or vice versa. It is a myth. You could use conventional oil in fall, then switch to synthetic in winter. Nothing bad would happen.

4. The down-side to synthetic oil

Most drivers never look under their hood. When you get an oil change every three months, there’s a professional inspecting your engine and making sure everything is okay. When you get an oil change once or twice a year, that’s not happening enough to prevent car problems.

If an engine develops a leak or begins to burn more oil than usual, the driver might not notice until months after the fact. The faster you identify a car problem, the cheaper and easier it will be to solve.

Switching to synthetic oil? Compensate for the difference by popping open your hood once a month. It’d be smart to do this on the first or last of the month, because that makes it easier to remember.

Check your fluid levels. Make sure oil and coolant are not mixing together. Look for splatters of oil. See a problem? Call your mechanic. All clear? Good! Plan to check again next month.

5. Synthetic is better for the environment

Used oil can seep into our groundwater, which provides drinking water to 51% of the U.S. population. Inevitably, used oil and other toxic wastes get illegally dumped, damaging our food and water supply (not to mention the well-being of people and animals who depend on those resources!).

Synthetic oil doesn’t eliminate this problem, but it does reduce the amount of harm that can be done. Note point #2 to see why. If a majority of drivers switched to synthetic oil, they would cut the amount of motor oil consumed in half. It doesn’t take a scientist to tell you that would benefit the environment.

6. Synthetic: Fast and efficient protection

Sludge develops when oil breaks down and collects on engine parts. If you make short trips and/or do a lot of stop-and-go driving, you’re at a high risk for engine sludge. This isn’t as likely for drivers with a longer commute. Their engine has time to warm up, which allows the oil to do its job (lubricate!).

There’s one more situation where you might need a higher level of protection. Do you use your vehicle to haul heavy items? If so, switch to synthetic. Your engine will thank you later. Are you an aspiring race-car driver? If so, fun fact: synthetic oil is the standard for NASCAR drivers.

So, should I use synthetic or conventional in my next oil change?

Some facts and insights to guide your decision:

First, you should know certain cars require synthetic oil. This is especially true for European and high-performance vehicles. If you’re not sure, check out your owner’s manual for more information.

Next, using the wrong oil could make your warranty null and void… so, this is IMPORTANT! Assuming it’s safe for you to use conventional oil, consider the following questions:

  • Does the temperature get super hot or cold in your hometown?
  • Are traffic jams (stop-and-go driving) common in your city?
  • Will your vehicle be used to tow or haul large objects?
  • Have you ever seen sludge build-up in your engine?
  • Do you drive less than ten miles in the average trip?
  • Is protecting the environment important to you?

If you said “YES” to three or more questions, then you would definitely benefit from switching to synthetic oil. If you said “YES” to one or two questions, then it might be worth consideration. Otherwise, you might as well stick with conventional oil.

Questions? Let me know in the comments.

Master mechanic, automotive expert and teacher, Audra Fordin is the author of End Auto Anxiety, CEO of Women Auto... More about Audra Fordin