Something to consider.
The garage that service/repair Mrs_Gs Cargo use Valvoline oils. According to the guy there the Cargo had a slight oil weap when we first took it to him. Since then its been serviced using Valvoline oil and the weap has stopped. Apparently the oil has an additive that 'conditions' oil seals.
Now it could just be a load of waffle but I have no reason to doubt what the guy at the garage is saying. After all he could have said the weap needs fixing and charged us for changing an oil seal.(I now trust this chap 100%, he's saved us a HUGE amount of money with his honest, no nonsense way of doing business).
Perhaps an oil change, using Valvoline oil, might be a cheap fix in your situation.