I can't get the exact details, these are older pictures, but the opinion is about 2 years between the green oil being commissioned to when the system was checked for operating issues. The green oil had been put in for test purposes.
That is about all I can find out about it, as people have moved on and I was not involved.
The thing is that strainer stank, I mean really stank. It was double bagged in a 5 gallon can and it just about blew our socks off when it was taken it out for the pictures.