Well I've seen this questions asked several times over the year. I have a cooler also and wondered about what to do. Soooo, I just got off the phone with Canton in CT and the tech guy said
"don't worry about it". The only way to get it all out is to blow air into the line. He said it's really messy to do and the small amount of
oil in cooler won't make a big difference.
Roscoe