Visually, you cannot tell the difference between new synthetic and conventional oil. There are two major differences, however. First, how they are made is a distinction. We’ve explained that synthetic oil is far more refined than conventional oil.

Second, the way they run in your car is worlds apart. Used motor oil shows a lot thicker and sludgy in conventional oil vs. synthetic oil, given the same amount of wear. Synthetic oil is by far better for performance. It protects the engine due to lower levels of friction. Additives help clean the engine of deposits. And, fewer impurities mean it burns cleaner, thickens far more slowly, and has fewer deposits to start.

The benefits of synthetic oil vs conventional oil:

• Fewer emissions
• Better fuel and oil economy
• Increased engine protection and wear from lower friction
• Longer intervals between oil changes
• Reduced engine drag from greater resistance to thickening
• Oil effectiveness/quality is more predictable and uniform
• Better all-weather protection
• Quicker engine start time
• Helps clean engine sludge and deposits

Synthetic oil is generally considered the best oil. It is designed for performance. However, that same manufacturing process makes it more expensive.