Hi guys

I have de-commissioned a denco downflow unit (removed gas) the system has had a leak. My question is
If the unit was going to re- used somewhere else
you would put virgin r407c in as the removed gas is now void! But if you where putting new gas in would you need to add oil? The compressor us sealed but it does say on use a certain type of oil?

In what circumstances would you have to add oil?

Thanks