That was back in the 90’s, when I lived on the OH/PA border. If someone does it now, it’s likely under the radar and you’d have to know someone who knows someone.
The guy I went to had a 1950’s era gas station with a matching hoist. He had to back my trailer onto the hoist, disconnect from my truck, and raise it just enough for him to get down in the pit and start spraying.
He was completely covered in his “oiling suit”, including a helmet.
He had an air compressor and spraying attachments especially for the oil. If I remember correctly, he had to modify the nozzle to let the oil come thru without clogging.
He started out using used motor oil, but went to bar & chain oil for chainsaws.
I’ve redone the wiring twice and a new floor three times. The paint is oxidized but the trailer is solid. It still sits outside but my horses and I are now retired so it stays covered with a boat tarp.