First, I'll point out that the site is far from abandoned; the refinery may be dismantled, but the tank farm, ship dock, rail siding and tanker truck terminal are all still very much in use.
I always assumed this system had been abandoned when the refinery part shut down, however a few months ago I decided to give the voice channels a listen. Not much to do during the early days of the pandemic, so I was spending a lot of time looking over some of this weirder stuff. Anyway, turns out there's still activity on the system frequencies, but with DCS tones, which tells me they've likely re-used the frequencies for conventional repeaters. I've been meaning to assemble the notes I made and add it to the database (and remove the Motorola system). I should probably get on that.
Anyway interestingly, I also discovered what sounds to me like a very weak Motorola control channel on 424.9875, and if you look that up in the TAFL it shows as licensed to Imperial Oil. Not sure what that's about, but I can never get a good enough signal to decode anything from it.
Edit: I've removed the Motorola system from the database. At some point I'll add the conventional repeaters once I figure out where those notes are.