did you do the oil cap dance test? loosen the cap dont remove it and see how much it dances... lil movement is good, some flopping around is marginal, if you have to have your hand above it so it doesnt fly away thats not good

another easy test is wait til it gets to about 30F outside and see if you can start it without a block heater, keep going to lower temps to see how low you can start it in, i think 20F without a block heater is good.. actually. i dont know if this test is for blowby.. but i would be assured if i could start my car in 20F