why would there be oil in the PVC valve going into the air filter

What is your question?

We just got a Toyota Avalon 2001 my husband change the valve gaskets and he noticed that there's oil going through the PVC valve into the air filter it uses up to 5 quarts of oil a week why would that be and what can we do to fix it.

What makes this problem better or worse?

driving it

How long has your 2001 Toyota Avalon had this problem?

two weeks