Do you use synthetic oil in a 1999 Mazda 626?

Yes, you can use synthetic oil in a 1999 Mazda 626. Synthetic oil offers better protection and performance, especially in extreme temperatures, compared to conventional oil. However, it's essential to check the owner’s manual for the recommended oil specifications and change intervals to ensure optimal engine health. If the engine has been running on conventional oil for years, consider a gradual switch to synthetic to avoid potential leaks.