If your car is still under any kind of warranty, stay with the intervals specified in the owner’s manual, and do not use synthetic unless your owner’s manual Oks it.
Beyond that, you will get many different opinions. Which is correct? I don’t know, but I don’t want to take a chance on a $4000 engine for lack of a $50 oil change.
I had someone tell me to change the oil filter without changing the oil (with synthetics). Someone more knowledgeable than a Pep Boys salesman, but I still discounted it.