OIL Base Primer for MOST exterior projects !
The Factory Primer would be Questionable to me, However, one thing for certain is, make sure the surface is clean and WAX free, they sometimes apply a thin wax coat to protect during shipping,
I read Mfg recommendations and if I can, I wash new siding that I am going to paint with TSP, Tri-Sodium-Phosfate,
I always use Oil based primer for exterior, and here's why ! Oil based primer takes a long time to dry and during this drying period, it has much longer to soak in, which causes WAY better gripping ability. Your Finish paint is no better than the Primer under it, meaning if the Primer comes off, the Finish is coming off with it, then you have RAW material exposed, many will probably disagree, but I am a retired, 30+ year vetran of the Paint game and this method seems to work best,,, don't misunderstand now, Latex is Fine for your finish, just use OIL BASED PRIMER for the best possible adhesion ! Blessings and Good Luck,,,, Steven