i have a 01 pt cruiser that the compression in #1 is 75 and #4 is about 50 what can be wrong with it

i took 31 plug out and it was drenched with oil none of the other ones were so i did a compression check on 1 and 4 because i didnt have to take the intake off to get to them i got 75 lbs on #1 and 55 on #4