There will be many opinions on this one. I feel it is just a marketing thing with the synthetic oils in an off the showroom car. I would drive a new car at least to the first OCI before putting synthetic in. This is just my opinion and I'm sticking to it.
Several years ago I think that was the case, on new engines today I think it's perfectly fine to put in syn right away. I can't see dumping good oil even if it's dino, on my vehicles I just wait until the first regular change to put in syn.
I would run the first batch of factory to 3 months or 2000 miles then dump it. Run synthetic and change that at 5000 on the odo. I would then proceed with normal interval of 6 months, 6000-7500 miles with high quality synthetics. Numerous UOA's on here prove that wear metals are higher in new engines, why leave the factory oil in? Plus the oil in some cases has been in the motor more than 6 months before the vehicle is even sold.
-2003 Toyota Tacoma PreRunner XtraCab, 2.7 Liter , Mobil1 Synthetic SS 5W-30.
ODO 9400 Miles.
-1995 Toyota 4-Runner 3.0 V6, Mobil1 Synthetic SS 10W-30.
ODO 91400 Miles.