What's the difference between a fully synthetic and a semi-synthetic engine oil?

All engine oils are made of base oils and additives. Fully synthetic engine oils contain 100% non-conventional, high-performance fluids. Semi-synthetic engine oils (also called "blends") contain a smaller percentage of these high-performance fluids in combination with conventional mineral oil. Mobil 1 is a fully synthetic motor oil.

Related Questions:

  1. Why is the choice of engine oil so important?
  2. Why is an engine oil’s ability to cleanse important?
  3. How does oil protect my engine?
  4. What is engine oil made from?
  5. Is it important to change oil and how often should I do this?
  6. How should I dispose of used oil?
  7. Will I really notice the difference if I don’t make frequent oil changes?
  8. Why not just keep topping up the engine oil?
  9. What's so good about synthetics?
  10. Why Mobil 1 and not another synthetic?
  11. Is Mobil 1 suited to 'stop-start' driving?
  12. Is Mobil 1 suited to long haul motorway driving?
  13. Is Mobil 1 suited to performance driving?
  14. Does Mobil 1 offer value for money?