Some choices are simple: iPhone over Android, steak over chicken, and regular over decaf ALL DAY LONG.

But when it comes to selecting the right lubricant for your engine, the matter isn’t always cut and dried. Both conventional and synthetic motor oils have their respective advantages and shortcomings. Which means the decision often boils down to factors like age and type of vehicle, individual driving habits, and of course, the almighty dollar.

Let’s pit synthetic vs conventional oil head-to-head to get a better handle on which is the right choice for your customer’s (or your) engine.  

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

Also known as mineral oil, conventional oil has been the industry standard for decades. Refined from crude petroleum, it comes in a wide variety of grades, temperature ranges, and quality levels. In fact, the molecules that make up conventional oil all have different shapes, sizes, and structures, too. And, it contains impurities that, over time, may affect its viscosity, or how easily it flows at different temperatures.

Synthetic oil, on the other hand, is chemically engineered and produced with additives for optimal performance. While it starts with a high-quality base oil, the refining process of synthetics allows for greater control over their molecular structure. As a result, synthetic oil molecules are more uniform in size and shape; they also contain fewer impurities than conventional oil molecules. Overall, synthetic oil is a more stable, cleaner-burning product.

The Advantages of Synthetic Oil

Besides looking better under a microscope, synthetic oil does come with several advantages over conventional oil.

Higher Viscosity Index: The consistency of synthetic oils is largely unaffected by temperature. So, while conventional oil typically becomes thicker at lower temperatures and thinner in extreme heat, synthetics won’t degrade or change viscosity based on the weather. This is especially beneficial for cold starts, or under harsh driving conditions.     

Fights Oxidation: The introduction of oxygen can cause conventional motor oil to break down faster and lose its lubricating properties. This often results in the formation of sludge and deposits, increased viscosity, and faster depletion of additives. It also requires more frequent oil changes. Synthetics, by contrast, are formulated with additives specifically designed to resist oxidation.     

Reduces Friction: Remember those uniform molecules in synthetic oil? Because they’re nearly identical, they can slip easily across each other, giving them much better film strength and lubricity vs. petroleum-based conventional oils. Better lubrication of moving parts translates to less power consumption, resulting in smoother running and more fuel-efficient engines.           

The Right Oil for the Job

Once you break down the science, it’s clear that synthetic oil tops conventional in most categories. But is it better in all scenarios? Consider the following factors:

  • Age and make of vehicle: Newer engines with tighter tolerances usually prefer the superior film strength and breakdown resistance of synthetic oil. It can also help extend the life of many older engines by reducing wear and tear on parts. However, in some cases the finer molecular structure and smoother-flowing nature of synthetics could actually harm older engines by increasing the chances of leaking, or grinding gears; this is where the slower flow of conventional oil may offer more effective lubrication.

  • Driving habits: Synthetic oil is designed to handle the higher temperatures and pressures of high-performance and turbocharged engines. So, if racing or street performance is on your agenda, the choice is pretty simple. Similarly, synthetics provide better engine protection if the vehicle is used for towing or hauling heavy loads; if it’s taken off-road or driven in congested/polluted areas; or if it makes frequent stops and starts.

  • Temperature resistance: This goes back to synthetic oil’s higher viscosity index and its resistance to extremes on both sides of the temperature spectrum. Unlike conventional oils, synthetics contain additives that prevent them from thinning in the heat and thickening or freezing in cold weather. Synthetics can also help reduce the temperature inside your engine by cutting down on heat-generating friction.    

  • Cost considerations: Synthetic oil is pricier than conventional oil, but you can also go longer between oil changes with it, so those costs tend to balance out in the long run. For regular driving or in mostly moderate conditions, the extra up-front cost of synthetic oil might not be worth it.         

Both conventional and synthetic motor oils have their respective advantages and shortcomings, which means the decision often boils down to factors like age and type of vehicle, individual driving habits, and of course, the almighty dollar.    

Synthetics: The Finer Points 

While synthetic motor oils stand out for their superior performance and longevity, understanding these two important aspects can further shore up your decision-making.

Synthetic Blends: Yes, there is a middle ground between conventional and fully synthetic oil. These blends are made by mixing together base oils of each type to form a combination with some of the same properties as full synthetics, but that costs a lot less. It may be preferred by some engine builders for its superior clingability to certain engine parts.

API Service Classifications: The American Petroleum Institute (API) evaluates every blend of motor oil to ensure it meets automakers’ minimum performance standards in areas like wear protection, fuel economy, and emissions. Basically, it’s a good way to tell whether the oil is safe to use in certain engines. API ratings cover oil for both gasoline and diesel vehicles, and they change periodically. For example, oil for all gas vehicles manufactured after 2010 comes with an SN classification; although in 2017, API introduced an SN+ designation for turbocharged engines.

Refining the Options

The choice between conventional and synthetic oil boils down to a few key factors. While synthetics are engineered for outstanding engine protection and performance in various conditions, they do cost more than conventional oil, which may be just fine for normal driving or those on a budget. Either way, confirming the type of oil that’s recommended by the vehicle’s manufacturer, and keeping up with regular oil changes, always helps engines run smoother and last longer.

And, to get your quick lube shop running like a well-oiled machine, look no further than Shopmonkey’s all-in-one oil change software. Request a free demo today and unlock the doors to faster, smarter management of your quick-lube shop.