Some current cars come with synthetic as factory fill, and the manufacturer of course recco's using synthetic when it is time to change it.
For Mobil 1 much of and sometimes all of the cost difference between it and conventional oil can be mitagated by watching for it to go on sale at walmart.
Some engine designs benefit, in fact may "need" a very thin oil for small oil passages in the engine. Synthetic can be an advantage on cold startup, in cold weather for an engine like that.
If you really want to know how you oil is doing, take a sample and send it to a lab for testing. I use blackstone lab, but there are others. Blackstone charges $25 for an analysis.
