Even the most responsible vehicle owners often don’t know what kind of oil is in their vehicle's engine without checking the owners’ manual first. And even if they do know their vehicle’s oil weight and viscosity, they may be clueless about whether they use synthetic or regular oil.
  

  
SYNTHETIC OIL VS. REGULAR
Conventional or “regular” motor oils, simply put, are pulled from the ground, sent through a refinery, and then poured into your engine. The molecules of conventional oil vary in size, which means that their viscosity, especially at extreme temperatures, can be less reliable than a synthetic oil. Conventional oil also breaks down more quickly, creates more engine sludge, and is cheaper than their synthetic counterparts.

Synthetic oils, although they start off as conventional oils, go through an additional engineering process in a lab. The steps taken and chemicals added during this process can vary based on the company producing them as well as the vehicular application the oil is intended for. For example, synthetics made for high-performance vehicles or for operating in extreme conditions may have different recipes. The additional engineering and additives create a synthetic oil with molecules that are much more uniform, lubricate more effectively, and last longer without breaking down.

SHOULD I USE SYNTHETIC OR REGULAR OIL IN MY VEHICLE?
In most use cases and for most vehicles, synthetic oil will outperform conventional oil. Although synthetics are more expensive up front than regular oils, their additional benefits generally make up for the extra cost. Synthetic oils:

• Lubricate better for longer and at higher temperatures.

• Break down more slowly, so you won't have to change it as often.

• Leave less sludge and debris in your engine.

Regular oils, on the other hand, while cheaper, can work better in older, simpler engines. If you drive a high-mileage, older vehicle, the slower flow of a conventional oil can coat the internal components of your engine more effectively, keep aging seals from springing leaks, and letting you squeeze as much mileage as possible from your motor.

The best way to see the type of oil your vehicle needs is to check your owner’s manual.
   

  
CAN YOU MIX SYNTHETIC OIL WITH REGULAR OIL?
Yes, you can mix conventional and synthetic oils in a pinch, but whenever possible, you should try to match the type of oil that's already inside your engine and recommended by your owner’s manual. While you won't damage your engine by mixing synthetics with conventional oil, some of the beneficial properties of synthetic oil may be reduced or changed when mixed. However, by sticking to your oil change intervals, any reduction in performance should be unnoticeable and remedied the next time you take your vehicle into the shop for new oil.