when you say "Oil", do you mean Automatic Transmission Fluid ?
Why would you want to put the ATF back into the transmission ?
There are previous threads about servicing the auto-transmission on the VE.
You will see that there are different levels of service.
For $100 or so, you can get a minor service, which doesn't achieve much.
A "full service" is a lot more. One trick to watch out for is that the correct ATF is used.
I had a full service earlier this week:
local Holden dealer quoted me $570, but my past experience of them, shared by most other Holden owners, is that they are thieving morons.
I went to a specialist auto-trans service, with a good reputation, and got the full service for $400 + GST.
Opinions vary as to the appropriate interval between services.
I was told that the correct ATF, Dexron-6, ought to last longer than earlier varieties.
Also, I do a lot of highway travelling in my VE - about 40,000 km each year.
The technician recommended that I come back in 50,000 km.
But there are plenty who like to service these components at shorter intervals.