You’ve probably been in this position at one point or another: you’re sitting in the lobby at the mechanic shop, waiting for an oil change, and the technician hands you a laminated card with various options on it. Perhaps you weren’t very well-versed in the differences between oils at that time, so you chose either the cheapest oil change (conventional oil) or the pricey one recommended by the mechanic (full-synthetic). While you may not have known what the difference was then, you can certainly learn about it now so that you can make an informed decision in the future.

Synthetic Oil vs Conventional Oil

(Pixabay / Vacho)

How did synthetic oil come about?

Synthetic oil was born out of the desire to have an oil that worked well in both hot and cold temperatures. Previously, conventional oil would get very runny when extremely hot and would move like molasses in January when very cold. You can imagine how this inconsistency could be a problem in a high-powered engine working in climates with varying temperatures.

Scientists worked to create synthetic oil in the 1930s and 1940s. The resulting solution was put to work in airplanes and other high-powered machinery used in WWII. Engineers and scientists have since continued to refine synthetic oil so that it works well in everything from sports cars to jet engines.

What can synthetic oil do that conventional oil can’t?

Synthetic oil is designed to handle the increased levels of heat and friction generated by high-powered engines. As people have demanded better vehicles and governments have cracked down on emissions, engineers have designed machines that run faster and burn hotter. The uniform molecules in the synthetic oil handle the heat better and don’t break down as quickly as conventional oil. Plus, the additives in synthetic oil can help lubricate and clean the engine. These additions also make it so that the oil is more viscous (thicker) so that it clings to the parts in the engine better, which helps things run more smoothly and generate less engine sludge.

Why is there such a price difference?

Synthetic oil is man-made, and there is a lot of time, energy, and engineering that goes into creating a product that does the things that synthetic oil does. While conventional and some (but not all) synthetic oils originally started as crude oil, the synthetic oil is intensely refined and mixed with additives and other oils. This extra level of refinement lets engineers and scientists regulate molecular structure within the oil, leading to a more uniform product that increases performance and lowers friction.

On the other hand, conventional oil is less refined, so its molecular structure is a little more inconsistent. This can lead to an increase in friction within the engine, and it can cause a build-up of “engine sludge.” While conventional oil isn’t necessarily a bad choice for your vehicle, it doesn’t have the ultra-refined properties of synthetic oil.

Does synthetic oil really last longer?

That is a good question, and it is also highly debated among mechanics and engineers. Some believe that due to the ultra-refined nature of synthetic oil, you should be able to drive two to three times longer on a single oil change. Others believe that synthetic and conventional oils are beneficial to your vehicle for the same amount of time.

So what should I choose?

Depending on the make, model, and year of your vehicle, you may not have a choice in the matter. Newer cars have started requiring semi or fully synthetic oils, and if that is true in your case, you should stick with the manufacturer’s recommendation. If your vehicle is older, your mechanic may recommend that you stick with the same kind of oil that you’ve always used, though he or she may feel that a switch from conventional to semi-synthetic may improve the life of your engine. Before you make a choice, make sure to read through your owner’s manual and ask your mechanic for a recommendation based on your car’s specifications.