Abstract: A polyethylene terephthalate film suited for motor insulation is described having the following:(a) an intrinsic viscosity of 0.80;(b) a lateral crystalline size of not greater than 65 Angstroms;(c) an extractable oligomer content of no more than 0.6% by wt.;(d) a hydrolytic lifetime of at least 500 hours;(e) a density within the range from 1.385 to 1.395;(f) no more than 3% by weight comonomer;(g) no more then 1.5% by weight of diethylene glycol as a comonomer;(h) a carboxyl content of no more than 25 milliequivalents per gram of polymer;(i) a particulate content of 0.1 to 2 weight % with the proviso that the polyethylene terephthalate film does not contain an end capping agent; and(j) an embrittlement time at 160.degree. C. of more than 100 days.