The large scale resin guys that work in 1/6 scale soak thiers in Castrol Super Clean prior to pinning for assembly, and after what happened today, I will agree.
Large parts have a tendency to soak up more lubricant from the mold, and that tends to draw deeper inside any pinholes in the resin (more surface, more micropinholes). For that reason they soak thier parts for several days or a month in Super Clean to get rid of the oils. Today I shot primer on an older Newman R &D X-38 return vehicle. It has been stripped after painting about two years ago, and when I hit it with primer today after washing with soap/water and wipedown with lacquer thinner, the primer fisheyed BADLY and I do mean BADLY. Thirty years of painting and I have not had a reaction this bad--will need to strip that and soak in Super Clean again to get the oils out.
Good luck with it....and its OK to use thinner primer than on metal figures. I like Citadel Black Primer, working from black up to the light colors.
Build to please yourself, and don't worry about what others think!
TI 4019 Jolly Roger Squadron, 501st Legion