I have no problems with my LiquiVac. I pump 45 times before initial drain, then about 15 more does the final trick.
I take the container to the corner gas station, and it's recycled.
The only time it gone rough was when I did four cars on one day. Dad's a cardio patient, and not allowed to "pump." (According to him, anyway...) So I really got a work out!
1998 C230 "Black Betty"