Someplace I read/say that is was bad to switch between regular oil and synthetic oil. That if your vehicle is using regular oil, switching to synthetic will cause the “seals” to dry out. Any truth to this quesion?
No. You can switch back and forth between regular and synthetic oil at any time.
Tester
Oils for cars are fully compatible; you can mix and match and switch back and forth. Make sure you have the right viscosity for the season; don’t use heavy grades in the winter.
When synthetic oils first came out years ago, there was some truth to that. That was a long time ago and far different oils today. Don’t worry.